UC-NRLF 


3D    6ES 


MEUHCAL    .SCHOOL 
OB8I&A1ISY 


NERVOUS  AND  MENTAL  DISEASE  MONOGRAPH  SERIES  No.  12 


Cerebellar  Functions 


BY 


DR.  ANDRE-p^OMAS 

(Ancient  Interne  des  Hopifaux  de  Paris) 


TRANSLATED  BY 


W.  CONYERS  HERRING,  M.D.,  of  New  York 
With  89  figures  in  the  text 


NEW  YORK 

THE  JOURNAL  OF  NERVO'US  AND  MENTAL  DISEASE 

PUBLISHING  COMPANY 

1912 


NERVOUS   AND  MENTAL  DISEASE 
MONOGRAPH   SERIES 

Edited  by 

Drs.  SMITH  ELY  JELLIFFE  and  WM.  A.  WHITE 
Numbers  Issued 

1.  Outlines  of  Psychiatry.    By  Wm.  A.  White,  M.D. 

2.  Studies  in  Paranoia. 

By  Drs.  N.  Gierlich  and  M.  Friedman 

3.  The  Psychology  of  Dementia  Praecox. 

By  Dr.  C.  G.  Jung. 

4.  Selected  Papers  on  Hysteria  and  other  Psychoneuroses. 

By  Prof.  Sigmund  Freud. 

5.  The  Wassermann  Serum  Diagnosis  in  Psychiatry. 

By  Dr.  Felix  Plaut. 

6.  Epidemic  Poliomyelitis.     New  York  Epidemic,  1907. 

7.  Three  Contributions  to  Sexual  Theory. 

By  Prof.  Sigmund  Freud. 

8.  Mental  Mechanisms. 

By  Wm.  A.  White,  M.D. 

9.  Studies  in  Psychiatry. 

New  York  Psychiatrical  Society 

10.  Handbook  of  Mental  Examination  Methods. 

By  Shepherd  Ivory  Franz, 
n.    The  Theory  of  Schizophrenic  Negativism. 

By  Professor  E.  Bleuler. 
12.    Cerebellar  Functions. 

By  Dr.  Andre-Thomas 


Copyright  1912 

BY 
THE  JOURNAL  OF  NERVOUS  AND  MENTAL   DISEASE 


PRESS  OF 

THE  NEW  ERA  PRINTING  COMPANY 
LANCASTER.  PA 


CONTENTS 


PART  FIRST 

EXPOSITION  OF  FACTS 

CHAPTER  I 
ANATOMY  OF  THE  CEREBELLUM 


CHAPTER   II 
EXPERIMENTATION  —  DESTRUCTION  OF  THE  CEREBELLUM   ..............     54 

CHAPTER   III 
EXPERIMENTATION   (CONTINUED)    ...................................     84 


CHAPTER   IV 
EXPERIMENTATION   (CONTINUED)    93 

CHAPTER   V 
SYMPTOMATOLOGY  OF  THE  AFFECTIONS  OF  THE  CEREBELLUM   101 

PART  SECOND 
INTERPRETATION 

CHAPTER   VI 
THE  CEREBELLUM  AND  THE  ORGANIC  FUNCTIONS  132 

CHAPTER   VII 
THE  CEREBELLUM  AND  SENSIBILITY 135 

CHAPTER   VIII 
THE  CEREBELLUM  AND  INTELLIGENCE 139 

CHAPTER   IX 

THE  CEREBELLUM  AND  MOTILITY  141 

BIBLIOGRAPHY 209 

INDEX 221 

iii 


THE  FUNCTIONS  OF  THE 
CEREBELLUM 


FIRST   PART 
EXPOSITION  OF  FACTS 


CHAPTER   I 

ANATOMY  OF  THE  CEREBELLUM 
I.  THE  ARCHITECTURE  OF  THE  CEREBELLUM 

The  cerebellum  is  an  unpaired  median  symmetrical  organ, 
situated,  in  man,  below  the  cerebral  hemispheres  which  cover  it 
entirely,  behind  the  corpora  quadrigeminl,  and  above  the  pons 
Varolii  and  the  medulla  oblongata  in  which  it  makes  a  deep 
groove  or  concavity  and  which  it  overlaps  largely  on  the  sides. 

With  its  furrowed  a^d  lamellated  appearance  it  is  related  to 
all  the  other  parts  of  the  central  nervous  system  in  which,  by 
volume,  it  occupies  the  second  place ;  it  is  but  a  misnomer  to  call 
it  the  "  little  brain  "  or  "  Kleinhirn  "  as  do  the  Germans  as  this 
name  is  neither  justified  by  morphology,  histology  nor  physiology. 

The  cortex  of  the  cerebellum  or  the  cerebellar  mantle,  which 
is  demonstrated  by  a  simple  macroscopic  examination,  constitutes 
but  one  portion  of  the  organ;  a  series  of  longitudinal  or  sagittal 
sections  gives  immediately  an  important  idea  of  its  architecture; 
From  the  surface  towards  the  interior  one  can  distinguish:  (i) 
the  cerebellar  cortex;  (2)  a  thick  layer  of  white  matter;  (3) 
collections  of  gray  matter  or  central  gray  nuclei.  In  man  there 
are  four  of  these  nuclei  for  each  half  of  the  organ,  the  corpus 
rhomboideum  or  cerebellar  olive  also  called  the  corpus  dentatum, 
the  nucleus  fastigii,  the  nucleus  globulosus  and  the  nucleus  em- 


2  THE    FUNCTIONS    OF    THE    CEREBELLUM 

boliformis  (Fig.  3).  Certainly  the  cortex  and  the  nuclei  have,  as 
we  shall  see  further  on,  very  intimate  relations  with  one  another, 
but  their  configuration  and  their  structure  is  so  dissimilar  that 
they  must  be  looked  upon  as  distinct  organs.  This  should  be 
the  same  with  the  cerebellum  as  with  the  cerebrum.  In  each 
cerebral  hemisphere  does  not  one  distinguish — as  well  from  the 
point  of  view  of  structure  as  of  function — the  cortex  and  the 
central  nuclei?  All  the  more  reason  to  do  the  same  for  the 
cerebellum  in  which  the  cortex  is  so  distinctly  differentiated  from 
the  rest  by  its  external  appearance  as  well  as  by  its  histological 
structure. 


Spop 

FIG.  i.     Section  of  Meynert.     Inferior  surface  of  the  cerebellum. 
(After  a  photograph.) 

AM,  anterior  wall;  B,  medulla;  Cv,  hemispheres  of  the  cerebellum; 
Epa,  anterior  perforated  space;  Fe  bundle  of  Ferre;  Floe,  flocculus;  /, 
insula;  i,  fissure  of  the  insula;  la,  anterior  convolutions  of  the  insula;  Ip, 
posterior  convolution  of  the  insula;  LF,  frontal  lobe;  LT,  temporal  lobe; 
Lc,  central  lobe;  Ldg,  digastric  lobe;  Lgr,  lobus  gracilis. 

This  conception  is  however  not  only  anatomical  but  physio- 
logical as  well ;  there  will  be  occasion  to  investigate  whether  there 
are  differences  observed  between  the  symptoms  which  are  pro- 
duced by  the  simple  destruction  of  the  cortex  in  animals  and 


ANATOMY    OF    THE    CEREBELLUM  3 

man,  and  those  produced  by  the  total  destruction  of  the  organ 
(both  cortex  and  central  gray  nuclei),  between  the •  phenomena 
produced  by  the  excitation  of  the  cortex  and  of  those  which 
follow  the  irritation  of  the  central  nuclei.  To  sum  up,  the  cere- 
bellar  cortex  is  an  organ  and  the  central  gray  nuclei  are  other 
organs;  there  exist  relations,  both  anatomical  and  physiological, 
between  the  two,  but  nevertheless  they  enjoy  an  independence 
sufficiently  marked  to  consider  them  as  distinct  organs. 

The  cerebellum  is  formed  of  a  median  or  central  part,  the 
vermis  or  median  lobe,  and  of  two  lateral  parts,  the  lateral  lobes 
or  hemispheres. 


FIG.  2.    Section  of  Meynert.     Superior  surface  of  the  cerebellum. 

Lqa,  anterior  quadrilateral  lobe;  Lqp,  posterior  quadrilateral  lobe; 
Lsli,  inferior  semi-lunar  lobe;  Lsls,  superior  semi-lunar  lobe;  NA,  nucleus 
amygdalus;  P,  foot  of  the  peduncle;  pFL,  falciform  fold  of  Broca;  Scf, 
circumferential  fissure  of  Vicq  d'Azyr;  SiV,  inferior  fissure;  Sma,  ante- 
rior marginal  groove;  SsV,  superior  fissure;  5" ta,  anterior  transverse 
fissure ;  Vcu,  culmen ;  Vde,  declive ;  Vsph,  sphenoidal  ventricle ;  XII, 
optic  chasm. 

The  vermis  in  the  animal  series  is  the  most  constant  part 
of  the  cerebellum;  it  alone  exists  in  the  inferior  vertebrates 
(fishes,  reptiles),  and  also  in  the  great  majority  of  birds.  It 
is  only  in  the  mammalia  that  the  lateral  lobes,  rudimentary  in 
certain  types  of  birds,  compare  in  their  development  with  the 
vermis.  Edinger,  from  the  point  of  view  of  phylogenetic  evolu- 


4  THE    FUNCTIONS    OF    THE    CEREBELLUM 

tion,  joins  the  vermis  and  the  flocculus  under  the  name  of  paleo- 
cerebellum;  the  lateral  lobes  which  appear  later  form  the  neo- 
cerebellum. 

In  man  the  limits  between  the  hemispheres  and  the  vermis 
on  the  superior  surface  are  somewhat  indistinct;  this  is  not  so 
on  the  inferior  surface,  where  the  pyramids  are  clearly  separated 
from  the  hemispheres  on  each  side  by  a  -deep  groove.  The  supe- 
rior surface  of  the  vermis  is  called  the  superior  vermis  and  the 
inferior  surface  the  inferior  vermis. 


FIG.  3.     Photograph  of  a  section  of  the  pons  and  the  cerebellum  of  man. 

(Stained  Wiegert-Pal.) 

Cj,  juxta-restiform  body;  Flp,  posterior  longitudinal  bundle;  fsme, 
fsmi,  arcuate  fibers,  external,  internal ;  Nem,  embolus ;  Ngl,  globulus ; 
Nt,  nucleus  fastigii ;  Oc,  cerebellar  olive ;  Pci,  inferior  cerebellar  peduncle ; 
Pcm,  middle  cerebellar  peduncle;  NVI,  nucleus  of  sixth  nerve;  VII., 
facial. 

In  animals  they  are  respectively  the  posterior  and  anterior 
vermis.  A  detailed  description  of  the  fissures  and  lobes  does  not 


ANATOMY     OF     THE     CEREBELLUM  5 

come  within  the  scope  of  this  work.  It  is  only  necessary  to  re- 
member that  the  cerebellum  is  divided  by  several  deep  fissures 
into  lobes;  these  are  divided  by  less  pronounced  fissures  into 
lobules  and  these  in  their  turn  into  lamellae.  The  fissures  of  the 
vermis  are  less  deep  than  of  the  lateral  hemispheres,  nevertheless 
there  is  an  apparent  continuity  between  the  lamellae  of  the  cere- 
bellar  hemispheres  and  those  of  the  vermis,  so  that  each  lobe  com- 
prised between  two  deep  fissures  may  be  considered  as  being 
formed  of  a  vermian  and  two  hemispheric  parts.  This  concep- 
tion, however,  is  purely  anatomical,  for  physiologically  it  seems 
preferable  not  to  confound  the  hemispheres  and  the  vermis. 

M.  and  Mme.  Dejerine  distinguish  five  primordial  lobes  in  the 
cerebellum  of  man :  ( i )  superior  lobe  or  lobe  of  the  principal 
mass  of  the  vermis;  (2)  posterior  lobe,  or  lobe  of  the  transverse 
lobule;  (3)  inferior  lobe  or  lobe  of  the  pyramid;  (4)  infero-in- 
ternal  lobe,  or  lobe  of  the  uvula;  (5)  infero-anterior  lobe  or  lobe 
of  the  nodule. 

Each  of  these  lobes  comprises  a  vermian  and  a  hemispheric 
portion.  The  superior  lobe  is  divided  into  four  secondary  lobes. 
The  lobe  of  the  lingula,  central  lobe,  lobe  of  the  culmen  and 
lobe  of  the  declive.  The  lobe  of  the  lingula  is  represented  in 
the  vermis  by  the  lingula  and  in  the  hemispheres  by  the  frenulse 
of  the  lingula;  in  the  same  way  the  central  lobe  comprises  the 
central  lobule  and  the  alae  of  the  central  lobule.  The  lobe  of  the 
culmen,  the  culmen  and  the  anterior  portion  of  the  quadrilateral 
lobe ;  the  lobe  of  the  declive  represents  the  declivus  and  the  poste- 
rior portion  of  the  quadrilateral  lobe. 

The  posterior  lobe  is  subdivided  into  the  superior  lobe  of  the 
transverse  lamellae  (folium  cacuminis  in  the  vermis  and  superior 
semilunar  lobe  in  the  hemispheres),  and  the  lobe  of  the  inferior 
transverse  lamellae  (tuber  valvulae  in  the  vermis  and  the  inferior 
semilunar  lobe  and  the  lobus  gracilis  in  the  hemispheres),  the  in- 
ferior lobe  or  lobe  of  the  pyramid  comprises  the  pyramid  in  the 
vermis  and  the  digastric  lobe  in  the  hemispheres. 

The  infero-internal  lobe  or  the  lobe  of  the  uvula  is  formed 
by  the  uvula  in  the  vermis,  and  the  tonsils  in  the  hemispheres. 

Finally  the  infero-anterior  lobe  or  lobe  of  the  nodule  is 
represented  in  the  vermis  by  the  nodule  and  in  the  hemispheres 
by  the  flocculus. 


6  THE    FUNCTIONS    OF    THE    CEREBELLUM 

The  figures  i  and  2  represent  the  superior  and  inferior  sur- 
faces of  the  cerebellum  in  man. 

The  nomenclature  of  the  lobes  and  fissures  is  purely  ana- 
tomical. The  theory  of  cerebellar  localization,  which  is  of  very 
recent  date,  does  not  up  to  the  present  repose  upon  a  basis  of 
facts  sufficiently  demonstrable. 

II.  HISTOLOGY  OF  THE  CEREBELLUM 

In  the  solution  of  a  physiological  problem  of  this  order  one 
cannot  omit  a  consideration  of  the  structure  of  the  cerebellum 
and  more  particularly  the  knowledge  that  has  been  acquired  of 
the  connections  which  unite  the  nerve  elements  or  different 
groups  of  cells  one  with  another.  The  results  obtained  by  stain- 
ing with  silver  chromate  by  Golgi  and  Ramon  y  Cajal  are  of 
primary  importance  from  this  viewpoint  (Figs.  4  and  5). 

Structure  of  the  Cortex. — Each  lobe  of  the  cortex  is  divided 
into  lobules  and  lamellae.  The  whole  histology  of  the  cortex  is 
thus  based  upon  that  of  a  lamella.  Each  lamella  is  divided  from 
the  surface  to  the  interior  into:  (i)  the  molecular  layer;  (2)  the 
granular  layer  and  (3)  the  white  substance. 

The  molecular  layer  is  occupied  by  star-shaped  cells  of  two 
kinds,  large  and  small.  The  small  cells,  more  superficial,  have 
the  form  and  properties  of  the  majority  of  multipolar  cells.  The 
large  cells  for  the  most  part  lie  deeper.  The  axis-cylinder  of  the 
large  star-shaped  cells  is  derived  from  the  body  of  the  cell  and 
takes  an  antero-posterior  direction;  after  a  long  course  it  ap- 
proaches a  Purkinje  cell  around  which  it  arborizes  and  forms  a 
sort  of  basket  or  envelope  (Kolliker),  but  before  this  it  gives  off 
at  regular  intervals  collaterals  which  arborize  in  the  same  manner 
around  other  Purkinje  cells.  Each  star-shaped  cell  of  the  molec- 
ular layer  has  thus,  dependent  upon  it,  a  large  number  of  Purkinje 
cells.  At  the  limits  of  the  molecular  layer  and  the  granular  layer 
there  are  found  a  large  number  of  the  Purkinje  cells :  the  largest 
in  size  of  the  elements  of  the  cortex,  and  considered  from  the 
physiological  point  of  view  as  playing  the  most  active  part. 

The  Purkinje  cells  are  notable  for  their  rich  protoplasmic 
expansions  which  run  through  the  whole  thickness  of  the  molec- 
ular layer.  The  body  is  voluminous  and  spherical  or  ovoid,  it  is 
continuous  with  one  or  two  large  protoplasmic  arborizations  upon 


ANATOMY    OF     THE     CEREBELLUM  7 

which  all  the  others  are  implanted.  These  protoplasmic  arboriza- 
tions or  dendrites  are  covered  with  thorny  projections  which  are 
perpendicularly  inserted;  they  terminate  freely.  The  axis  cylin- 
der is  directed  towards  the  interior,  at  first  to  the  granular  layer 
and  then  to  the  white  substance,  it  gives  off  one  or  two  collaterals 
which  mount  to  the  molecular  layer  where  they  end. 


A 


FIG.  4. 


Semi-schematic  transverse  section  of  a  cerebellar  convolution  in  a 

mammal.     (After  Ramon  y  Cajal.) 

A,  molecular  zone ;  B,  granular  zone ;  C,  zone  of  the  white  substance ; 
a,  Purkinje  cell,  front  view;  b,  small  star-shaped  cells  of  the  molecular 
layer;  d,  final  descending  arborizations  which  surround  the  cells  of 
Purkinje;  e,  star-shaped  superficial  cells;  /,  large  star-shaped  cells  of  the 
granular  layer;  g,  granules  with  their  ascending  axis-cylinders  bifurcated 
at  T;  h,  mossy  fibers;  j,  neuroglia  cell  with  branches;  m,  neuroglia  cell  of 
the  granular  layer ;  n,  climbing  fibers ;  o,  ascending  collaterals  from  the 
axis-cylinders  of  the  Purkinje  cells. 


8 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


The  Purkinje  cells  contain  a  number  of  large  chromatic  gran- 
ules and  are  traversed  by  numerous  neurofibrillse. 

The  granular  layer  is  almost  entirely  composed  of  an  agglom- 
eration of  small  cellular  elements  of  a  spheroidal  shape.  Each 
one  possesses  protoplasmic  prolongations  and  an  axis-cylinder 
prolongation.  The  protoplasmic  prolongations  are  few  in  num- 
ber (three  or  four),  thin,  short,  and  terminate  by  a  slight  ar- 
borization. The  axis-cylinder  mounts  into  the  molecular  layer 
and  divides  in  the  form  of  a  T,  into  two  horizontal  branches ; 
each  of  these  runs  through  the  molecular  layer  for  a  long  distance 


FIG.  5.     Semi-schematic  longitudinal  section  of  a  cerebellar  convolution. 

(After  Ramon  y  Cajal.) 

A,  molecular  layer;  B,  granular  layer;  C,  layer  of  the  white  substance ; 
a,  ascending  axis-cylinders  from  the  granules ;  c,  bifurcation  of  this  axis- 
cylinder  and  the  formation  of  a  parallel  fiber;  d,  Purkinje  cell  seen  in 
profile ;  e,  granular  terminal  extremity  of  the  parallel  fibers ;  /,  axis- 
cylinders  of  the  Purkinje  cells. 

and  terminates  freely,  but  they  enter  into  contact  along  the  whole 
of  their  course  with  the  terminations  and  protuberances  of  the 
ramifications  of  the  Purkinje  cells.  In  the  granular  layer  also 
there,  are  found  some  large  star-shaped  multipolar  cells  or  cells  of 
type  II  of  Golgi,  the  axis-cylinders  of  which  arborize  very  freely 
around  the  body  of  the  cell  and  thus  enclose  in  a  sort  of  network 
a  very  large  number  of  the  "  granules "  or  small  cells  of  the 
granular  layer.  The  protoplasmic  prolongations  terminate  either 
in  the  granular  layer  or  in  the  molecular  layer. 


ANATOMY     OF     THE     CEREBELLUM  9 

The  white  substance  is  formed  by  a  mass  of  myelinated  nerve 
fibers  which  go  in  opposite  directions;  the  fibers  of  one  kind  are 
centrifugal  and  originate  in  the  cerebellar  cortex,  and  the  others 
are  centripetal  and  terminate  in  the  cortex.  The  centrifugal 
fibers  are  derived  entirely  from  the  Purkinje  cells  which  have 
been  described. 

The  centripetal  fibers  are  of  two  kinds:  the  mossy  fibers  of 
Cajal,  and  the  climbing  fibers.  The  mossy  fibers  of  Cajal  are  so 
called  because  they  present  nodular  thickenings  bristling  with 
short  divergent  expansions,  which  resemble  the  moss  covering 
trees.  They  arborize  in  the  granular  layer  and  consequently 
they  enter  into  relations  with  the  granules. 

The  climbing  or  creeping  fibers  ramify  principally  in  the 
molecular  layer  and  attach  themselves  to  the  ascending  arboriza- 
tions of  the  Purkinje  cells;  they  terminate  in  varicose  and  plexi- 
form  arborizations. 

The  centripetal  or  terminal  fibers  are  fibers  of  association, 
peduncular  fibers,  and  fibers  of  projection.  The  peduncular  fibers 
originate  in  the  middle  and  inferior  cerebellar  peduncles.  It  is 
probable,  if  they  exist  at  all,  that  fibers  which  originate  in  the 
central  gray  nuclei  are  very  few  in  number.  Association  fibers 
unite  the  neighboring  lobules  and  lamellae  to  one  another. 

The  structure  and  the  division  of  the  neuroglia  and  the  other 
interstitial  elements  does  not  offer  any  interest  in  a  purely  physio- 
logical study.  On  the  other  hand  the  light  thrown  by  histological 
examinations  upon  the  morphology  of  the  nervous  elements  and 
their  reciprocal  relations  is  of  some  help  in  following  the  path 
of  excitations  from  the  periphery  to  the  cerebellum,  and  vice 
versa. 

The  stimulus  carried  by  a  centripetal  fiber  is  transmitted  simul- 
taneously to  several  Purkinje  cells  either  directly  (climbing  fibers) 
or  indirectly  by  the  intermediation  of  the  granules  or  the  star- 
shaped  cells  of  the  molecular  layer.  Each  Purkinje  cell  is  in  re- 
lation with  neighboring  Purkinje  cells  by  means  of  the  recurrent 
collaterals  of  the  axis  cylinders. 

The  association  fibers  establish  functional  relations  between 
the  cellular  elements  of  neighboring  lobules  and  lamellae.  It  is 
finally  upon  the  Purkinje  cells  that  all  centripetal  excitations 
are  concentrated ;  these  elements  in  their  turn  are  the  only  ones 


IO  THE    FUNCTIONS    OF    THE    CEREBELLUM 

whose  axis  cylinders  project  themselves  to  the  central  gray  nuclei 
(fibers  of  projection).  Justly,  therefore,  the  Purkinje  cell  is 
considered  the  truly  active  element  of  the  cerebellar  cortex. 

Thus  organized  the  cerebellar  cortex  appears  fitted  to  propa- 
gate and  reinforce  impressions  which  come  to  it  from  the 
periphery. 

Structure  of  the  Central  Gray  Nuclei. — The  cerebellar  olive 
and  its'accessory  nuclei,  i.  e.,  nucleus  globosus  and  nucleus  emboli- 
formis,  have  the. same  structure.  Three  kinds  of  elements  are 
found  in  them :  numerous  myelinated  fibers,  a  large  number  of 
cells  and  terminal  arborizations.  The  cells  are  of  medium  si-ze, 
multipolar  and  elongated.  From  their  bodies  dendrites  are  given 
off  which  arborize  in  dividing  dichotomously  and  direct  them- 
selves externally.  The  axis  cylinders,  on  the  contrary,  turn 
towards  the  center  or  hilum  of  the  cerebellar  olive,  i.  e.,  towards 
the  superior  cerebellar  peduncle.  Between  the  cells  there  are 
numbers  of  terminal  arborizations  dividing  dichotomously  several 
times. 

The  cells  of  the  nucleus  fastigii,  or  nucleus  of  the  tegmentum, 
are,  on  the  contrary,  large  multipolar  vesiculated  cells,  analogous 
to  the  cells  of  Bechterew's  and  Deiters'  nuclei.  The  bodies  are 
large,  the  protoplasmic  expansions  few  and  slightly  ramified, 
thick  and  very  long. 

III.     THE  CONNECTIONS  OF  THE  CEREBELLUM 

The  nerve  fibers  which  run  through  the  white  substance  of 
the  cerebellum  belong  to  various  systems.  Some  of  them  termi- 
nate in  the  cerebellum :  these  are  the  afferent  fibers ;  others  orig- 
inate in  the  cerebellum  and  terminate  either  within  or  without  it: 
these  are  the  efferent  fibers ;  or  in  another  territory  of  the  cere- 
bellum at  a  point  more  or  less  remote  from  that  of  their  origin, 
on  the  same  side  or  on  the  opposite  side;  these  are  the  fibers  of 
projection  or  the  fibers  of  association. 

The  connections  of  the  cerebellum  with  the  other  centers  are 
made  by  means  of  three  large  bundles,  or  peduncles :  the  inferior 
cerebellar  peduncle,  the  middle  cerebellar  peduncle,  and  the  supe- 
rior cerebellar  peduncle.  What  is  the  distribution  of  the  efferent 
and  afferent  fibers  in  these  three  systems  of  bundles ;  what  are  the 


ANATOMY     OF     THE     CEREBELLUM  I  I 

origins  of  the  afferent  fibers,  and  what  is  the  destination  of  the 
efferent  fibers?  These  are  the  problems  which  have  been  solved 
in  a  great  measure  by  the  study  of  secondary  degenerations  fol- 
lowing focal  lesions  in  man,  and  by  sections  or  experimental  de- 
structions in  animals.  The  experimental  method  offers  the  valu- 
able advantage  of  being  able  to  change  the  location  and  extent  of 
the  lesions,  and  it  is  by  this  means  that  the  most  precise  informa- 
tion concerning  the  origin  and  termination  of  the  cerebellar  bun- 
dles has  been  acquired. 

The  results  obtained  by  a  study  of  degenerations  agree 
with  those  obtained  by  histological  methods,  such  as  the  method 
of  Cajal,  by  impregnation  with  silver  chromate.  Employing  this 
method  in  small  mammals  this  author  was  able  to  follow  the 
cerebellar  fibers  to  their  origins  and  their  terminations.  But  the 
method  is  insufficient  for  systems  of  long  fibers.  These  cannot  be 
traced  save  by  studying  secondary  degenerations. 

I.   Afferent  Fibers 

The  afferent  fibers  follow  two  paths  in  entering  the,  cerebel- 
lum, the  inferior  and  median  cerebellar  peduncles.  The  inferior 
cerebellar  peduncle  contains  fibers  of  bulbar,  medullary  and 
spinal  origin ;  the  middle  cerebellar  peduncle  contains  fibers  of 
pontine  origin.  In  fact,  the  spinal  cord  is  but  a  relay  station 
between  the  periphery  of  the  sensory  paths  and  the  cerebellum, 
the  medulla  oblongata,  an  intermediary  between  the  mid-brain 
and  the  cerebellum,  and  the  pons  is  but  a  station  between  the 
cerebral  cortex  and  the  cerebellum.  This  is  what  anatomy  and 
a  study  of  secondary  degenerations  teaches. 

The  Inferior  Cerebellar  Peduncle  or  Restiform  Body 

This  is  formed  of  two  parts :  the  spinal  and  the  medullary. 
The  spinal  part  is  represented  by:  (a)  the  direct  cerebellar  tract 
and  some  fibers  of  the  posterior  cord;  (&)  the  tract  of  Goll  and 
the  tract  of  Burdach.  The  cerebellum  receives  besides  these  a 
bundle  of  fibers  which  does  not  traverse  the  inferior  cerebellar 
peduncle ;  these  are  the  fibers  from  the  tract  of  Cowers. 

Spinal  Part. — (a)  The  direct  cerebellar  tract,  first  described 
by  Foville,  and  later  by  Flechsig,  originates  in  man  between  the 


12 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


first  lumbar  segment  and  the  twelfth  dorsal.  This  limit  is  dis- 
puted and  it  is  carried  higher  by  Schultze  who  indicates  the 
tenth  dorsal  segment,  and  by  Kahler  and  Pick,  who  indicate  the 
ninth  dorsal  segment,  whereas,  Flechsig  lowers  it  to  between  the 
second  and  third  lumbar  segment.  Long,  Rothmann,  as  well  as 
Barbacci,  Pellizzi  and  Flatau,  admit  that  in  the  dog  the  lowest 
fibers  appear  in  the  lumbo-sacral  region.  In  the  rabbit  the  exist- 


FIG.  6.     Section  of  the  spinal  cord  of  a  fetus  aged  8i  months.    Lower 

dorsal  regions.  (Stained  by  the  method  of  Pal.) 
The  pyramidal  tract,  crossed  and  direct,  which  is  not  yet  myelinated 
shows  in  white.  The  fibers  which  take  their  origin  in  the  column  of 
Clarke  are  directed  9utwards  towards  the  periphery  and  constitute  the 
direct  cerebellar  tract.  Cc,  column  of  Clarke;  ffd,  fibers  coming  from  the 
column  of  Clarke  and  directed  towards  the  periphery  to  form  the  direct 
cerebellar  tract ;  Pyc,  crossed  pyramidal  tract ;  Pyd,  direct  pyramidal  tract. 

ence  of  any  such  fibers  was  not  found  by  Singer  and  Miinzer, 
Sarbo,  Miinzer  and  Wiener,  and  Bochenek.  Bing  suggests  the 
hypothesis  that  the  direct  cerebellar  tract  commences  at  a  more  or 
less  high  level  in  animals  according  to  the  greater  or  less  develop- 
ment or  absence  of  the  tail.  Whatever  the  explanation  may  be 


ANATOMY    OF    THE    CEREBELLUM  13 

it  is  possible  that  variations  exist  according  to  the  species  of 
animals.  The  direct  cerebellar  tract  occupies  the  most  posterior 
and  external  part  of  the  lateral  cord,  limited  within  by  the 
crossed-pyramidal  tract,  and  without  by  the  sub-meningeal  tissue, 
the  more  posterior  fibers  adjoin  the  extremity  of  the  posterior 
horn;  the  most  anterior  fibers  enter  almost  into  contact  with  the 
posterior  fibers  of  Cowers'  tract.  It  increases  in  volume  progres- 
sively as  one  examines  it  at  the  higher  levels  of  the  dorsal 
cord;  it  does  not  increase  perceptibly  above  the  first  dorsal  seg- 
ment and  keeps  the  same  volume  until  it  reaches  the  medulla.  It 
originates  in  the  column  of  Clarke  of  the  same  side;  this  in  its 
turn  extends  from  the  first  lumbar  root  to  the  first  dorsal  root. 
The  origin  of  the  direct  cerebellar  tract  in  the  column  of 
Clarke  is  demonstrated:  (i)  by  histological  methods,  especially 
by  the  method  of  Cajal,  where  one  can  see  the  nerve  fibers  com- 
ing from  the  column  of  Clarke  traverse  the  lateral  tract  and 

FIGS.  7  to  II.  Degenerations  of  the  direct  cerebellar  tract  and  the 
tract  of  Gowers  after  experimental  section  of  the  spinal  cord  in  the 
superior  cervical  region  of  the  cat. 


FIG.  7.     Section  of  the  spinal  cord  at  the  level  of  the  first  cervical  root. 
Cal,  anterior-lateral  segment;  Fb,  tract  of  Burdach;  Fd,  direct  cere- 
bellar tract;  FG,  tract  of  Gowers;  Fg,  tract  of  Goll. 

engage  in  the  direct  cerebellar  tract;  (2)  by  pathological  anat- 
omy. When  this  tract  is  severed  by  a  transverse  section,  or  is 
primarily  degenerated  in  consequence  of  an  hereditary  disease, 
the  cells  of  the  column  of  Clarke  atrophy  in  the  planes  adjacent  to 
the  lesion.  In  the  case  of  unilateral  lesions  this  atrophy  occurs 


14  THE    FUNCTIONS    OF    THE    CEREBELLUM 

only  on  the  same  side,  which  proves  that  the  fibers  of  the  direct 
cerebellar  tract  do  not  cross  in  the  cord,  and  so  come  homolater- 
ally  from  Clarke's  column.  At  the  level  of  the  medulla,  the  direct 
cerebellar  tract  bends  backwards  and  penetrates  the  restiform 
body  or  inferior  cerebellar  peduncle,  in  which  it  occupies  the  cen- 
tral part,  and  then  ascends  into  the  cerebellum  and  terminates  in 
the  anterior  portion  of  the  cortex  of  the  superior  vermis  (Auer- 
bach,  Bechterew,  Patrick,  Thomas,  Pellizzi,  Bruce,  Lewandowsky, 
Bing). 

The  fibers  terminate  some  on  the  same  side  and  others  on 
the  opposite  side  after  decussation  (Figs.  7  to  10).  The  propor- 
tion of  the  direct  fibers  to  the  crossed  fibers  is  disputed.  Pellizzi 


XII 


FIG.  8.     Section  of  the  medulla  at  the  level  of  the  olives  and  the  external 

segment  of  the  nucleus  of  Burdach. 

Crst,  restiform  body;  Fd,  direct  cerebellar  tract;  ffd,  fibers  of  the 
direct  cerebellar  tract,  turning  around  the  descending  root  of  the  fifth 
pair  to  enter  the  restiform  body;  FG,  tract  of  Cowers;  Ftp,  posterior 
longitudinal  fasciculus;  lo,  latero-olivary  ascending  tract;  NB,  nucleus  of 
Burdach;  NeB,  external  nucleus  of  the  tract  of  Burdach;  NG,  nucleus  of 
the  tract  of  Goll;  Nl,  nucleus  of  the  lateral  tract;  Oi,  inferior  olive;  Py, 
pyramid;  Vs,  descending  root  of  the  fifth  pair;  XII,  hypoglossal  nerve. 

considers  the  decussation  total,  Mott  says  there  is  a  partial 
decussation.  Andre-Thomas  and  Edinger  consider  that  there  is 
a  decussation  of  the  majority  of  the  fibers,  whereas,  v.  Monakow 
states  that  all  of  the  fibers  are  direct.  It  seems  established,  how- 
ever, that  the  majority  of  the  fibers  decussate  and  this  opinion  is 
also  maintained  by  Bing. 

It  is  known  on  the  other  hand  that  the  cells  of  Clarke's  column 
are  plunged  in  a  network  of  nerve  fibers,  nourished  by  the  fibers 


ANATOMY    OF    THE    CEREBELLUM  1 5 

of  medium  length  from  the  posterior  roots.  The  inferior  extrem- 
ity of  Clarke's  column,  according  to  the  experiments  of  Mott  and 
Margulies  on  the  monkey  receives  fibers  from  the  lumbar  and 
sacral  roots,  whereas,  according  to  Nageotte,  the  posterior  roots 
below  the  third  lumbar  do  not  furnish  any  fibers  to  Clarke's  col- 
umns. If  this  last  fact  were  definitely  shown  it  would  have  a 
certain  physiological  importance  since  the  first  lumbar  roots  inner- 
vate only  the  proximal  portion  of  the  lower  limb,  and  certain 
authors  hold  that  the  cerebellum  exercises  a  much  more  active 
influence  over  the  proximal  than  over  the  distal  extremity  of 
the  leg. 


FIG.  9.    Section  of  the  medulla  at  the  level  of  the  olives  and  the 
restiform  body. 

Crst,  restiform  body;  fcp,  fibers  of  the  posterior  column  going  to  the 
restiform  body  (external  posterior  arcuate  fibers)  ;  Fd,  ffd,  direct  cere- 
bellar  tract;  Fg,  tract  of  Cowers;  Flp,  posterior  longitudinal  fasciculus; 
lo,  latero-olivary  ascending  tract;  NeB,  external  nucleus  of  the  tract  of 
Burdach;  Oi,  inferior  olives;  Py,  pyramid;  Vs,  descending  root  of  the 
fifth  nerve;  XII,  hypoglossal  nerve. 

The  cells  of  Clarke's  columns  are  in  relation  principally  with 
the  posterior  roots  of  the  dorsal  region.  The  posterior  cervical 
roots  do  not  send  any  fibers  to  the  column  of  Clarke.  Conse- 
quently, the  direct  cerebellar  tract  does  not  transmit  any  periph- 
eral excitation  from  the  arms.  The  excitations  from  this  origin 
without  doubt  follow  another  path.  From  what  has  preceded 
we  may  conclude  that  if  the  physiological  conduction  follows  the 
same  route  as  the  Wallerian  degeneration  the  direct  cerebellar 
tract  transmits  to  the  cerebellum  excitations  or  impressions  which 
come  from  the  periphery,  and  especially  from  that  territory  in- 


i6 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


nervated  by  the  twelve  posterior  dorsal  roots  and  the  first  lum- 
bar. That  is  to  say,  excitations  which  come  from  the  trunk  and 
the  proximal  portion  of  the  legs.  The  direct  cerebellar  tract  is 
not  considered  as  a  path  of  transmission  of  conscious  or  sensory 
impressions,  whether  superficial  or  deep.  It  is  generally  con- 
sidered as  transmitting  stimuli  coming  from  the  deep  tissues, 
bones,  muscles,  articulations,  and  not  from  the  cutaneous 
surfaces. 


FIG.  10.  Section  of  the  medulla  below  the  emergence  of  the  fifth 
nerve  and  of  the  cerebellum  at  the  level  of  the  spreading  out  of  the  de- 
generated fibers  of  the  restiform  body.  For  the  indications  see  the  two 
previous  cuts. 

Ctr,  trapezoid  body;  ND,  nucleus  of  Deiters;  Ndl,  dentate  nucleus; 
O soa,  superior  olive  and  accessory  olivary  nucleus ;  PCS,  superior  cere- 
bellar peduncle;  Rm,  median  fillet  of  Reil;  Ve,  vermis;  Vs,  descending 
root  of  the  fifth;  VII,  facial  nerve. 

(b)  Cowers'  Tract  (Figs.  7  to  12). — Gowers'  tract  is  situated 
in  the  lateral  cord  immediately  in  front  of  the  direct  cerebellar 
tract,  and  on  the  border  of  the  circumference;  it  is  a  marginal 


ANATOMY    OF    THE    CEREBELLUM  I/ 

tract;  it  has  the  form  of  a  triangle,  the  summit  of  which  is  di- 
rected towards  the  lateral  horn  of  the  gray  substance  and  the 
base  towards  the  periphery  of  the  cord. 

Some  fibers  originate  in  the  lumbar  regions,  but  most  of  them 
come  from  the  dorsal  regions  (Mott).  The  existence  of  fibers 
originating  in  the  cervical  region  has  not  been  shown.  The 
origins  of  this  tract  are  both  direct  and  crossed.  This,  accord- 
ing to  Edinger,  proves  that  the  cells  occupy  the  posterior  horn,  for 
Mott  the  lateral  horn,  for  Gombault  and  Philippe  the  cells  of  the 
anterior  horn,  and  for  Bechterew  the  cells  which  surround  the 
central  region  of  the  gray  matter.  According  to  Andre-Thomas 
and  J.  Ch.  Roux,  the  cells  of  origin  would  be  situated  at  the  base 
of  the  anterior  horn. 


lo 


FIG.  II.     Section  of  the  medulla  above  the  emergence  of  the  fifth  nerve 

prepared  to  show  the  course  of  Cowers'  tract. 

FG,  tract  of  Gowers;  Pctn,  middle  cerebellar  peduncle;  PCS,  superior 
cerebellar  peduncle;  Rl,  lateral  fillet  of  Reil;  Rm,  median  fillet  of  Reil; 
Ds,  descending  root  of  the  fifth;  Vm,  small  motor  root  of  the  fifth. 

At  the  level  of  the  medulla  the  fibers  of  Gowers'  tract  pass 
immediately  outside  the  nucleus  of  the  lateral  tract  of  the  cord, 
within  which  they  partly  lose  themselves  (Andre-Thomas),  the 
rest  of  the  fibers  follow  an  ascending  path  in  the  pons,  winding 
about  the  superior  cerebellar  peduncle  at  its  emergence  from  the 
cerebellum,  and  terminate  in  the  ventral  portion  of  the  vermis,  or 

3 


18 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


the  anterior  vermis  (Mott,  Tooth,  Pellizzi,  Hoche,  and  Andre- 
Thomas).  After  a  decussation  almost  total,  a  very  small  portion 
terminates  in  the  nucleus  fastigii  (Auerbach,  Andre-Thomas). 

The  cells  of  origin  of  Cowers'  tract  enter  into  relation  with- 
out doubt  with  the  terminal  arborizations  of  a  certain  number  of 
the  fibers  of  the  posterior  roots,  and  this  tract,  doubtless,  does 
nothing  but  transmit  stimuli  from  the  periphery. 

To  sum  up,  the  two  tracts  which  establish  relations  between 
the  spinal  cord  and  the  cerebellum,  both  end  in  the  vermis  and 
do  not  furnish  any  fibers  to  the  hemispheres. 


FIG.  12.  Degeneration  of  the  posterior  column  of  the  direct  cerebellar 
tract  and  of  Cowers'  tract  in  a  case  of  compression  of  the  spinal  cord  at 
the  third  dorsal  root  (method  of  Marchi).  Level  of  the  eighth  cervical 
root. 

Fb,  tract  of  Burdach;  Fd,  .direct  cerebellar  tract;  FG,  tract  of 
Cowers;  Fg,  tract  of  Coll. 

(c)  Fibers  of  the  Posterior  Cord. — Their  existence  is  doubted 
by  Flechsig;  they  are  admitted,  on  the  other  hand,  by  Edinger, 
Darkschewitsch,  Freud,  Obersteiner,  Pellizzi  and  Andre-Thomas 
(Fig.  9).  These  fibers  are  direct  and  perhaps  crossed  (Edinger, 
Obersteiner,  Mott  and  Sherrington,  and  Tooth).  They  are  far 
less  numerous  than  the  fibers  of  the  direct  cerebellar  tract. 
They  leave  the  tracts  of  Goll  and  Burdach  at  the  level  of  the 


ANATOMY    OF    THE    CEREBELLUM  19 

medulla,  and  direct  themselves  toward  the  restiform  body  in 
which  they  occupy  the  central  part,  intimately  intermingled  with 
the  fibers  of  the  direct  cerebellar  tract. 

Medullary  Part,  (a)  Fibers  of  the  Nuclei  of  the  Posterior 
Columns. — Their  existence  is  disputed,  denied  by  Flechsig,  Ed- 
inger,  Obersteiner  and  Van  Gehuchten,  and  admitted  by  Bech- 
terew,  Darkschewitsch  and  Freud,  Ferrier  and  Turner,  and  Vegas. 
They  would  take  their  origin  in  the  nuclei  of  Goll  and  Burdach, 
that  is  to  say,  in  the  nuclei  which  receive  the  long  fibers  of  the 
posterior  root. 

If  the  participation  of  the  nucleus  of  Gollr  and  the  nucleus  of 
Burdach,  in  the  formation  of  the  restiform  body  appears  debat- 
able this  is  not  the  case  with  the  superior,  external  part  of  the 
nucleus  of  Burdach,  also  called  the  nucleus  of  v.  Monakow,  or  the 
nucleus  of  the  restiform  body.  This  nucleus  is  distinguished 
by  its  large  cells  richly  provided  with  protoplasmic  prolongations, 
from  the  cells  of  the  nuclei  of  Goll  and  Burdach,  which  are  far 
smaller.  Darkschewitsch  and  Freud,  Vegas  and  Blumenau  were 
the  first  to  insist  upon  the  relations  of  this  nucleus  to  the  resti- 
form body.  Unilateral  destructions  of  the  cerebellum  are  fol- 
lowed by  the  atrophy  and  disappearance  of  the  cells  of  the  nu- 
cleus of  v.  Monakow,  on  the  same  side.  This  fact  is  shown  in 
animals  by  experimental  physiology,  and  in  man  by  pathological 
anatomy  (Andre-Thomas).  These  fibers  are,  consequently, 
direct  fibers,  going  from  the  medulla  to  the  cerebellum  on  the 
same  side,  but  it  is  impossible  to  say  whether  they  are  distributed, 
either  exclusively  or  preferentially  to  the  vermis,  or  to  the  lateral 
lobe. 

The  nucleus  of  v.  Monakow  also  receives  fibers  from  the  tract 
of  Burdach;  fibers  which  are  nothing  but  a  continuation  of  the 
posterior  cervical  and  superior  dorsal  roots.  One  is  led,  there- 
fore, to  consider  this  nucleus  as  an  important  relay  station  be- 
tween the  peripheral  excitations  which  come  from  the  arm,  from 
the  neck,  and  from  the  superior  part  of  the  trunk,  on  the  one 
side,  and  the  cerebellar  cortex  on  the  other.  It  is  probable  that 
the  nucleus  of  v.  Monakow  plays  the  same  part  in  relation  to  the 
posterior  cervical  roots  that  the  column  of  Clarke  does  in  relation 
to  the  dorsal  and  superior  lumbar  roots. 


2O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

(b)  Fibers  of  the  Nucleus  of  the  Lateral  Columns  of  the 
Medulla. — These  fibers   have  been   described  by   Bechterew,  v. 
Monakow  and  Andre-Thomas.     The  nucleus  of  the  lateral  col- 
umn atrophies  after  a  unilateral  destruction  of  the  cerebellum 
and  on  the  same  side  as  the  lesion.     These  fibers  are  therefore 
direct.     The  place  of  their  termination,  vermis  or  hemisphere,  is 
still  undecided.     The  nucleus  of  the  lateral  column  receives  be- 
sides some  fibers  of  the  tract  of  Cowers,  and  may  be  looked  upon 
as  a  new  relay  station  between  the  spinal  cord  and  the  cerebellum. 

(c)  Olivary  Part. — This  is  the  most  important  of  the  medul- 
lary cerebellar  parts,  particularly  in  man,  where  the  olives  attain 
their  maximum  development.     The  destruction  of  a  cerebellar 
hemisphere  is  accompanied  by  a  retrograde  atrophy,  direct,  of  the 
restiform  body,  and  crossed,  of  the  inferior  olive.     These  cells 
atrophy   and   disappear    (Meynert).      This    is   a    constant    fact 

(Fig-  13)- 

The  fibers  which  take  their  origin  in  the  medullary  olive  and 
in  the  accessory  olivary  nuclei  antero-internal,  and  postero-exter- 
nal,  decussate  in  the  median  raphe  with  those  of  the  opposite  side 
and  follow,  before  penetrating  the  restiform  body,  either  the 
periphery  of  the  medulla,  after  having  turned  around  the  pyramid 
(zonal  cerebellar  olivary  fibers  of  Mingazzini),  or  the  superior 
external  segment  of  the  internal  arcuate  fibers  (retro-  and  in- 
tertrigeminal  fibers  of  Mingazzini).  These  fibers  are  so  called 
because  they  traverse,  or  limit  behind,  the  descending  root  of  the 
fifth  nerve. 

The  olivary  fibers  occupy  the  periphery  of  the  restiform  body, 
whereas  the  center  is  formed  by  the  direct  cerebellar  tract,  and 
the  fibers  of  the  posterior  columns.  After  section  of  the  resti- 
form body  in  the  dog,  degeneration  of  the  fibers  can  be  followed 
to  the  cortex  of  the  superior  vermis,  principally  of  the  same  side, 
as  well  as  to  the  hemispheric  cortex  in  continuation  with  the 
lamellae  of  the  vermis  (Andre-Thomas,  Klimoff,  Keller  and 
Probst).  Similar  observations  have  been  made  by  Mott,  but  it 
has  been  impossible  in  these  experiments  to  trace  the  olivary 
fibers. 

In  the  higher  monkeys  and  above  all  in  man,  the  medullary 
olive  takes  on  a  considerable  development;  it  doubles  on  itself 
several  times,  and  it  is  the  same  thing  in  the  case  of  the  cere- 


ANATOMY     OF     THE     CEREBELLUM 


21 


bellar  olive.  There  exists  a  certain  parallelism  in  the  develop- 
ment of  these  two  formations.  In  man  the  degenerations  of  the 
olivary  fibers  have  been  followed  to  the  nucleus  dentatus,  and  the 
nucleus  emboliformis  by  Babinski,  Nageotte,  and  Andre-Thomas. 
Babinski  and  Nageotte  give  the  names  olivo-ciliary  to  these 
fibers. 

FIGS.  13  to  16.  Transverse  sections  of  the  medulla,  the  pons  and  the 
thalamic  region  in  a  case  of  softening  of  the  left  hemisphere  of  the  cere- 
bellum. Weigert-Pal  staining. 


FIG.  13.  Section  of  the  medulla.  Crossed  atrophy  of  the  olive.  Di- 
rect atrophy  of  the  restiform  body.  In  this  case  the  pyramid  is  equally 
atrophied  in  consequence  of  a  lesion  situated  in  the  peduncular  path. 

Cj,  juxta- restiform  body;  Crst,  restiform  body;  Fare,  arcuate  fibers; 
Flp,  posterior  longitudinal  fasciculus;  Fs,  solitary  bundle;  Nab,  nucleus 
ambiguus;  Noe,  postero-external  accessory  olivary  nucleus;  Noi,  antero- 
internal  accessory-olivary  nucleus;  O,  inferior  olive;  Py,  pyramid;  SRg, 
reticulated  gray  substance;  SRa,  reticulated  white  substance;  Tub,  ac, 
acoustic  tubercle;  X,  pneumogastric  nerve;  XII,  hypoglossal  nerve;  Vsd, 
descending  root  of  fifth  nerve. 

The  olivary  fibers,  consequently,  have  a  double  destination, 
viz.,  the  cerebellar  cortex,  and  the  central  gray  nuclei  (nucleus 
dentatus  and  emboliformis). 


22  THE    FUNCTIONS    OF    THE    CEREBELLUM 

Holmes  and  Stewart  have  attempted  utilizing  the  method  of 
secondary  degenerations  in  man,  to  define  the  relations  of  the 
olive  to  the  cerebellar  cortex.  They  have  obtained  the  following 
results :  ( I )  each  olive  is  in  connection  with  the  contra-lateral 
half  of  the  cerebellum;  (2)  the  olivo-cerebellar  fibers  terminate 
in  the  lateral  lobes,  and  probably  also  in  the  vermis.  The  fibers 
going  to  the  central  gray  nuclei  are  certainly  very  few ;  there 
exists  according  to  the  same  authors  a  definite  relation  between 
the  different  parts  of  the  inferior  olives  and  the  accessory  olivary 
nuclei  on  the  one  side,  and  the  different  zones  of  the  cerebellar 
cortex  on  the  other. 

(a)  The  lateral  portion  of  the  olives  are  in  connection  with 
the  lateral  portion  of  the  cerebellar  cortex  on  the  opposite  side. 
(b)  The  median  extremities  of  the  inferior  olives  and  the  antero- 
internal  accessory  olivary  nuclei  sends  fibers  probably  to  the 
vermis  and  the  median  portion  of  the  lateral  lobes,  (c)  The 
dorsal  fold  of  the  olive  is  particularly  in  relation  with  the  superior 
face  of  the  cerebellum,  (d)  The  ventral  fold  is  rather  in  relation 
with  the  inferior  face. 

The  medullary  olives  receive  the  terminal  arborizations  of 
the  central  bundle  of  the  tegmentum ;  they  do  not  receive  any  other 
fibers  from  the  cortex.  The  central  bundle  of  the  tegmentum  is 
formed  by  fibers  which  take  their  origin  in  the  reticulated  sub- 
stance of  the  tegmentum  at  the  level  of  the  medulla,  from  the 
pons  and  from  the  sub-optic  region.  The  medullary  olive  unites 
thus  the  mesencephalon  and  the  rhombencephalon  of  the  same 
side  to  the  cortex,  and  to  the  cerebellar  olive  of  the  opposite  side. 

The  Middle  Cerebellar  Peduncle 
(Fig.    14) 

The  middle  cerebellar  peduncle  is  a  large  bundle  of  transverse 
fibers  interposed  between  the  anterior  surface  of  the  pons  and 
the  cerebellum.  The  middle  cerebellar  peduncle  attains  its  max- 
imum development  in  the  higher  apes  and  in  man,  and  the  degree 
of  its  development  is  proportional  to  that  of  the  pons  and  the 
pyramidal  tract  on  the  one  hand,  and  the  lateral  lobe  of  the 
cerebellum,  including  the  dentate  nucleus  on  the  other. 

The  study  of  secondary  degenerations  and  of  retrograde  atro- 


ANATOMY     OF     THE     CEREBELLUM  23 

phies  has  shown  that  the  fibers  of  the  middle  cerebellar  peduncle 
are  nothing  but  the  prolongations  of  the  axis  cylinders  of  the 
cells  of  the  pontine  nuclei  of  the  opposite  side.  Nevertheless, 
some  fibers  come  from  the  most  external  part  of  the  homolateral 
pontine  nuclei  (Andre-Thomas).  Besides,  some  fibers  take  their 
origin  from  the  gray  substance  of  the  pontine  tegmentum.  Is 


FIG.  14.  Transverse  section  of  the  pons.  To  the  right,  degeneration 
of  the  superior  cerebellar  peduncle  (Psc),  atrophy  of  the  middle  cere- 
bellar peduncle  (Pcm)  ;  to  the  left,  atrophy  of  the  central  bundle  of  the 
tegmentum  (Fee}. 

Fpoa,  Fpom,  Fpop,  anterior,  middle  and  posterior  transverse  bundles 
of  the  middle  cerebellar  peduncle;  NVm,  motor  nucleus  of  the  fifth;  Os, 
superior  olive ;  SgPo,  gray  substance  of  the  pons ;  VP,  peduncular  tract ; 
W,  valve  of  Vieussens;  /,  small  focus  of  softening. 

it  possible  that  some  fibers  have  an  inverse  direction  ?  That  is  to 
say,  do  they  go  from  the  cerebellar  cortex  to  the  gray  substance  of 
the  pons?  The  middle  cerebellar  peduncle  does  not  contain  any 
commissural  fibers  between  the  two  hemispheres. 


24  THE    FUNCTIONS    OF    THE    CEREBELLUM 

It  is  also  established  that  the  fibers  of  this  peduncle  terminate 
exclusively  in  the  cerebellar  cortex ;  none  of  them  go  to  the  central 
ganglia.  All  these  fibers  are  destined  for  the  lateral  lobe ;  it  has 
not  been  shown  that  the  vermis  receives  any. 

The  arciform  or  pre-pyramidal  nucleus  which  is  attached  to 
the  anterior  border  of  the  medullary  pyramid  also  atrophies 


FIG.  15.  Transverse  section  of  the  pons  (superior  extremity).  De- 
generation of  the  right  superior  cerebellar  peduncle  (Pcs).  Atrophy  of 
the  central  bundle  of  the  tegmentum  (Fee)  to  the  left. 

Ncs,  central  superior  nucleus;  Rl,  lateral  fillet  of  Reil;  Rm,  median 
fillet  of  Reil ;  Strp,  Stns,  Sine,  stratum  profundum  superficial  and  cen- 
trale  of  the  middle  cerebellar  peduncle  (Pcm).  For  other  indications  see 
the  preceding  cuts. 

after  unilateral  destruction  of  the  cerebellum,  and  this  atrophy  is 
crossed.  The  fibers  which  leave  it  accompany  the  olivary  fibers 
to  reach  the  cerebellum,  passing  through  the  restiform  body,  or 
they  may  follow  the  middle  cerebellar  peduncle.  The  arciform 


ANATOMY    OF     THE     CEREBELLUM  25 

nucleus  is  perhaps  nothing  but  the  inferior  extremity  of  the 
pontine  nucleus,  of  which  the  lowest  groups  of  cells  are  lodged 
in  front  of  the  pyramids. 

The  relations  of  the  cerebral  cortex  with  the  gray  substance 
of  the  pons  have  been  established  by  secondary  degenerations, 


FIG.  16.     Vertico-transverse  section  of  the  encephalic  isthmus  at  the 
level  of  the  posterior  part  of  the  optic  thalamus  and  the  red  nucleus.    The 
cut  should  be  reversed  and  represents  the  left  side.     Atrophy  of  the  red 
nucleus  (NR)  and  radiations  from  the  tegmentum  (RC). 
CL,  body  of  Luys;  Fm,  bundle  of  Meynert;  Thnm,  median  nucleus  of  the 

thalamus;  Ihne,  external  nucleus  of  the  thalamus;  //,  optic  tract. 

consecutive  to  focal  lesions  in  the  cerebral  cortex,  or,  of  its  fibers 

of  projection  in  the  internal  capsule  and  the  cerebral  peduncle. 

A  large  number  of  the  fibers  of  the  cerebral  peduncle,  or 


2,6  THE    FUNCTIONS    OF    THE    CEREBELLUM 

crus-cerebri,  of  which  the  origin  is  exclusively  cortical,  lose  them- 
selves in  the  anterior  surface  of  the  pons.  This  fact  is  already 
sufficiently  proven  by  the  difference  in  volume  which  exists  in  the 
normal  state  between  the  number  of  fibers  contained  in  the  crus, 
and  the  number  contained  in  the  pyramid,  and  still  more  by  the 
large  number  of  granular  bodies  which  occupy  the  pontine  nu- 
cleus in  the  case  of  secondary  degeneration  of  the  crus.  These 
cortico-pontine  fibers  all  stay  on  the  same  side  of  the  pons. 

The  relations  of  the  gray  substance  of  the  pons  and  that  of 
the  cerebellum  are,  on  the  contrary,  crossed ;  the  result  is  that  each 
pontine  nucleus  is  an  intercalated  post  between  the  cerebral 
cortex  of  the  same  side  and  the  cerebellar  cortex  of  the  opposite 
side. 

What  are  the  territories  of  the  cerebral  cortex  which  are  in 
connection  with  the  cerebellar  cortex  through  the  intermediation 
of  the  pontine  nuclei?  They  are  those  which  furnish  fibers  to 
the  crus-cerebri,  and,  consequently,  primarily  the  sensori-motor 
zone — the  frontal  ascending,  parietal  lobes,  and  the  paracentral 
lobules.  The  external  tract  of  the  crus,  or  the  bundle  of  Tiirck, 
terminates  exclusively  in  the  superior  third  of  the  anterior  sur- 
face of  the  pons.  It  takes  its  origin  from  the  middle  segment  of 
the  second  and  third  temporal  convolutions  (M.  and  Mme. 
Dejerine).  Finally,  some  fibers  follow  the  internal  bundle  of  the 
crus,  and  come  from  the  orbital  lobe  (Dejerine  and  Andre- 
Thomas). 

There  should  result  from  these  anatomical  relations  a  func- 
tional association  of  considerable  importance  between  the  cere- 
bellar cortex  and  the  cerebral  cortex,  an  association  capable  of 
throwing  light,  in  a  certain  measure,  upon  the  physiological  mech- 
anisms of  the  cerebellum;  especially  if  one  reflects  upon  the 
fact  that  the  cortical  zones  of  the  cerebrum,  which  are  projected 
anatomically  and  physiologically  upon  the  cerebellar  cortex,  are 
sensory-motor  zones,  and  a  zone  (second  and  third  temporal  con- 
volutions) which  many  authors  consider  as  the  center  of  impres- 
sions of  labyrinthine  origin. 

To  sum  up,  and  to  close  the  chapter  of  the  afferent  paths, 
whereas,  the  inferior  cerebellar  peduncle  or  restiform  body  brings 
into  relation  the  cortex  of  the  vermis,  and  the  adjacent  parts  of 
the  cerebellar  hemispheres,  with  the  spinal  cord,  the  medulla  and 


ANATOMY     OF     THE     CEREBELLUM  '2.J 

t 

the  mid-brain,  the  middle  cerebellar  peduncle  serves  as  a  tie 
between  the  cerebral  cortex  and  the  cortex  of  the  cerebellar 
hemispheres.  The  comparative  examination  of  the  neuro-axis 
in  the  animal  series  shows  that  there  is  a  constant  parallelism 
between  the  development  of  the  pons  and  the  median  cerebellar 
peduncles  and  the  cerebral  cortex. 

II.    Efferent  Fibers 

In  the  same  way  that  the  afferent  fibers  follow  the  path  of 
the  inferior  cerebellar  peduncle  and  the  median  cerebellar  pe- 
duncle to  penetrate  the  cerebellum,  the  efferent  fibers  for  the 
most  part  pass  through  the  superior  cerebellar  peduncle;  some 
come  out  of  the  cerebellum  through  the  internal  segment  of  the 
restiform  body  or  the  juxta-restiform  body.  A  very  small  num- 
ber follow  the  inferior  cerebellar  peduncle. 

The  Superior  Cerebellar  Peduncle 

The  superior  cerebellar  peduncle  is  a  large  bundle  which  goes 
from  one  cerebellar  hemisphere  to  the  red  nucleus  and  to  the 
optic  thalamus  of  the  opposite  side  (Figs.  15  to  20).  It  has  been 
by  a  study  of  secondary  degenerations  in  animals  that  the  origins 
o'f  this  bundle  have  been  defined.  It  was  admitted  in  the  first 
place  that  it  came  from  the  red  nucleus  (Mahaim  and  M.  and 
Mme.  Dejerine) .  The  experiments  of  Marchi,  Ferrier  and  Turner, 
Russell  and  Andre-Thomas,  have  shown  definitely  that  it  comes 
from  the  cerebellum,  not  from  the  cerebellar  cortex  but  from  the 
rhomboid  body  or  the  dentate  nucleus. 

The  fibers  of  the  superior  cerebellar  peduncle  decussate  in 
the  pontine  tegmentum,  decussation  of  Wernekink,  with  those  of 
the  contra-lateral  peduncle ;  the  decussation  is  complete. 

After  its  decussation  the  superior  cerebellar  peduncle  divides 
into  two  branches,  ascending  and  descending  (Ramon  y  Cajal, 
Andre-Thomas) . 

The  ascending  branch,  by  far  the  most  important,  follows  an 
ascending  path  and  traverses  the  red  nucleus,  to  which  it  gives  a 
certain  number  of  fibers,  before  terminating  in  the  optic  thala- 
mus (principally  the  ventral  portion  of  the  external  nucleus, 
Figs.  19  and  20).  It  is  possible  that  the  red  nucleus  furnishes 


28 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


some  descending  fibers  to  the  superior  cerebellar  peduncle,  in 
any  case  these  fibers  would  be  few. 

The  descending  branch,  much  more  slender,  terminates  in  the 
nucleus  reticularis  tegmenti  pontis  (Andre-Thomas,  Fig.  17). 


Imi-'  "•      \ 
ffiSlfilS^  - 


FIG.  17.  Section  at  the  level  of  the  superior  third  of  the  pons.  De- 
generation of  the  superior  and  middle  cerebellar  peduncles  after  the 
destruction  of  the  left  half  of  the  cerebellum  in  the  dog.  Termination  of 
the  superior  branch  of  the  superior  cerebellar  peduncle  in  the  nucleus 
reticularis  tegmenti  pontis. 

Flp,  posterior  longitudinal  fasciculus ;  Nrl,  nucleus  of  the  lateral  fillet 
of  Reil;  Nrtg,  nucleus  reticularis  tegmenti  pontis;  Pcm,  middle  cere- 
bellar peduncle;  PCS,  superior  cerebellar  peduncle;  Py,  pyramid;  RL, 
lateral  fillet  of  Reil;  Rm,  median  fillet  of  Reil;  Sgr,  gray  substance  of  the 
pons;  X,  zone  of  degeneration  in  the  median  reticulated  substance  inde- 
pendent of  the  cerebellar  lesion;  IV,  nervous  patheticus;  Vpnt,  small 
motor  root  of  fifth  nerve. 

The  nerve  current  transmitted  to  the  optic  thalamus  by  the 
superior  cerebellar  peduncle  ends  finally  in  the  cerebral  cortex 
through  the  intermediary  of  the  thalamo-cortical  fibers.  On  the 
other  hand  the  fibers  which  go  to  the  red  nucleus  form  an  arbori- 


ANATOMY     OF     THE     CEREBELLUM 


29 


zation  around  cells  the  axis  cylinders  of  which  go  to  the  spinal 
cord  after  a  decussation  in  the  pontine  tegmentum  (v.  Monakow, 
Rothmann,  Probst  and  Pawlow),  and  form  v.  Monakow's 
bundle,  or  the  rubro-spinal  tract  of  Van  Gehuchten.  This  tract 
has  not  been  followed  up  to  now  except  in  animals,  particularly 
in  the  macaque,  it  is  situated  in  the  lateral  column  immediately 
in  front  of  the  pyramidal  bundle  (pre-pyramidal  bundle  of 
Andre-Thomas).  Its  existence  has  not  been  demonstrated  in 
man. 


B 


Ri 


FIG.  18.  The  cut  has  by  mistake  been  reversed.  The  right  side,  should 
be  the  left  and  vice-versa.  The  same  mistake  has  been  made  in  the  fol- 
lowing cuts.  Degeneration  of  the  red  nucleus. 

BrQp,  brachium  of  the  posterior  quadrigeminate  body;  Cgi,  internal 
geniculate  body;  Flp,  posterior  longitudinal  fasciculus;  Fk,  fontain- 
artige  Hauben  Kreuzung ;  Ln,  locus  niger ;  NR,  red  nucleus ;  P,  peduncle ; 
RC,  capsule  of  the  red  nucleus  and  radiations  of  the  tegmentum;  Rm, 
median  fillet  of  Reil;  Tga,  anterior  quadrigeminal  tubercle;  III,  nervus 
motor  ocularis  communis. 

.The  superior  cerebellar  peduncle  thus  establishes  fairly  direct 
relations  between  the  cerebellum  on  one  hand  and  the  cerebrum 
and  spinal  cord  on  the  other. 


3O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

In  a  recent  work  v.  Monakow  has  made  a  study  of  the  red 
nucleus  in  mammals  and  in  man,  and  from  his  researches  he 
concludes  that  this  nucleus  is  made  up  of  two  secondary  nuclei. 

The  one  with  large  disseminated  cells  in  the  dorso-lateral 
part  of  the  pontine  tegmentum  forms  a  reticulated  nucleus 
(nucleus  magnocellularis  of  Hatschek).  The  other  accompanies 
the  bundles  which  traverse  the  red  nucleus  but  occupies  mostly 
the  frontal  extremity  and  is  formed  of  small  cells  (nucleus  par- 
vocellularis of  Hatschek).  The  first  is  phylogenetically  the  oldest 
and  is  more  important  in  quadrupeds,  in  anthropoids  and  in  man 
the  nucleus  parvocellularis  takes  on  the  greater  development. 

The  nucleus  magnocelluris  which  gives  rise  to  the  rubro- 
spinal  bundle  is  very  voluminous  in  lower  mammals,  and  is  rudi- 
mentary in  man.  The  fibers  which  arise  from  the  nucleus  parvo- 
cellularis rise  immediately  after  decussation  in  the  pontine  teg- 
mentum in  the  neighborhood  of  the  fillet,  and  in  the  dorsal  por- 
tion of  the  tegmentum.  The  nucleus  parvocellularis  it  seems  has 
also  some  important  relations  with  the  frontal  lobe  (as  has  been 
established  by  M.  and  Mme.  Dejerine).  The  structure  and  con- 
nections of  the  red  nucleus  become  complicated  in  direct  propor- 
tion to  the  development  of  the  frontal  lobes  and  the  cerebellar 
hemispheres. 

The  Internal  Segment  of  the  Restiform  Body  or  Juxta-restiform 
Body.     The  Cerebello-vestibular  Bundle. 

The  cerebellum  has  such  important  relations  with  the  nuclei 
of  the  vestibular  nerve  and  the  internal  segment  of  the  restiform 
body  that  many  authors  have  described  phenomena  of  degenera- 
tion which  follow  sections  of  the  vestibular  nerves  analogous  to 
those  which  follow  the  destruction  of  the  cerebellum. 

The  root  of  the  eighth  nerve  is  divided  into  two  branches,  the 
cochlear  and  the  vestibular. 

The  fibers  of  the  vestibular  branch  terminate  in  three 
medullary  nuclei.  The  nucleus  of  Deiters,  the  nucleus  of  Bech- 
terew,  and  the  triangular  nucleus.  Some  fibers  are  distributed  in 
the  nucleus  of  the  tegmentum  (Andre-Thomas). 

The  nucleus  of  Deiters  occupies  the  angle  in  the  pontine  teg- 
mentum formed  by  the  descending  root  of  the  fifth  nerve  and 
the  restiform  body,  or  the  inferior  cerebellar  peduncle.  It  is  a 


ANATOMY    OF     THE     CEREBELLUM  3! 

nucleus  composed  of  large  cells ;  it  is  continuous  above  and  behind 
on  the  side  of  the  cerebellum  with  the  nucleus  of  Bechterew,  sit- 
uated on  the  border  of  the  fourth  ventricle ;  below  with  a  column 


e  - 


-  .:  \        '  N         '  ,{/"<  *V    '    f"-,>      -'••'*    "    iC-*'V-     -'•••'   '•*"'    .V^        '•   >.  *•     '-',' '  -'-'-"--1"    *""^ 

f   '         '"' L     '  "if        rt  V*fJ*^-'"''  '•  '-    ..- "/*-'.  '    '  -  *, ~;  ^       V"£^        a"  '         •'"""*"> 

UuU^.^cH..^JL^tig|^gg:^  . 


JL.LHL 


FIG.  19.  Vertico-transverse  section  at  the  level  of  the  middle  third  of 
the  optic  thalamus.  Radiations  of  the  superior  cerebellar  peduncle  in  the 
thalamus.  (Same  case  as  in  Figs.  17  to  27.) 

dp,  posterior  internal  capsule;.  Line,  external  medullary  fold;  Lmi, 
internal  medullary  fold;  Ne,  external  thalamic  nucleus;  Ni,  internal 
thalamic  nucleus;  NL,  lenticular  nucleus;  Pith,  inferior  peduncle  of 
thalamus;  RTh,  thalamic  radiations;  Tga,  anterior  pillar  of  the  trigone; 
VA,  band  of  Vicq  d'Azyr;  Tr,  reticular  zone. 


of  gray  substance  lying  alongside  the  internal  border  of  the  resti- 
form  body  and  which  contains  a  certain  number  of  little  bundles 
which  have  a  vertical  direction.  These  little  bundles  form  the 


32  THE    FUNCTIONS    OF    THE    CEREBELLUM 

internal  segment  of  the  restiform  body,  or  better,  the  juxta-resti- 
form  body  (old  ascending  auditory  root,  or  root  of  Roller). 

We  have  given  these  bundles  the  name  of  cerebello-vestibular 
bundles  because  they  are  composed  of  two  kinds  of  fibers  (Figs. 
21  and  22)  :  descending  fibers  from  the  vestibular  root  of  the 


-Zr 


UL 1& 


FIG.  20.  Vertico-transverse  section  at  the  level  of  the  anterior  third 
of  the  optic  thalamus.  Ultimate  termination  of  the  degenerated  fibers  of 
the  superior  cerebellar  peduncle  in  the  thalamus. 

AL,  loop  of  the  lenticular  nucleus ;  Nc,  external  nucleus  of  the 
thalamus ;  dp,  posterior  internal  capsule ;  Nath,  anterior  thalamic  nucleus ; 
NL,  lenticular  nucleus;  RTh,  thalamic  radiations;  VA,  band  of  Vicq 
d'Azyr;  Tr,  reticular  zone. 

eighth  pair  and  fibers  coming  from  the  central  gray  nuclei  of  the 
cerebellum.  Both  of  them  lose  themselves  in  the  column  of  gray 
substance  which  accompanies  them  and  which  is  a  prolongation 
of  the  nucleus  of  Deiters.  The  existence  of  these  fibers  has 


ANATOMY    OF    THE    CEREBELLUM 


33 


been  shown  by  the  method  of  experimental  degeneration  after  a 
section  of  the  eighth  pair,  and  after  destruction  of  the  lateral 
half  of  the  cerebellum. 

The  triangular  nucleus  is  a  nucleus  composed  of  small  cells 
applied  by  its  base  to  the  antero-lateral  angle  of  the  fourth 
ventricle. 

Ci-st 


FIG.  21.  Section  of  the  medulla  below  the  olives.  Degenerations  of 
the  descending  cerebellar  tract,  of  the  restiform  body  and  of  the 
cerebello-vestibular  bundles. 

Crst,  restiform  body;  Fcda,  anterior  portion  of  the  descending  cere- 
bellar tract;  Fcdp,  posterior  portion  of  the  descending  cerebellar  tract; 
Fcv,  cerebellar-vestibular  tracts;  Flp,  posterior  longitudinal  fasciculus; 
NVII,  facial  nucleus;  Py,  pyramid;  Rm,  median  fillet  of  Reil;  Vs,  de- 
scending root  of  fifth  nerve. 

The  cerebellum  furnishes  also  some  fibers  to  the  vestibular 
root,  and  to  the  juxta-restiform  body.  The  nucleus  of  the  teg- 
mentum  is  the  principal  origin,  but  it  is  probable  that  the  globo- 
sus  and  the  emboliformis  (Koesel),  and  perhaps  even  the  dentate 
nucleus,  furnish  a  certain  number  of  fibers ;  none  of  them  seem  to 
come  from  the  cerebellar  cortex. 

The  whole  of  the  central  gray  nuclei  of  each  half  of  the  cere- 
bellum thus  enters  into  relation  with  the  two  vestibular  nerves, 
with  a  certain  preference  for  those  of  the  same  side.  The  direct 
fibers  are  no  other  than  the  internal  arcuate  fibers  which  .run 


34 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


along  the  lateral  border  of  the  fourth  ventricle  before  reaching 
the  nuclei  of  Deiters  and  Bechterew,  and  the  external  arcuate 
fibers  which  traverse  the  white  substance  passing  outside  the 
dentate  nucleus.  The  crossed  fibers  pass  through  the  anterior 
commissure  of  the  cerebellum  and  the  bundle  of  the  uncus  (Rus- 
sell and  Andre-Thomas),  which  turns  around  the  superior  cere- 
bellar  peduncle  below  its  emergence  from  the  cerebellum  (cere- 
bello-bulbar  bundle  of  Van  Gehuchten)  (Figs.  23  and  27). 


FIG.  22.  Section  of  the  medulla  passing  through  the  olives  and  the 
external  nucleus  of  the  column  of  Burdach.  Termination  of  the  degen- 
erated fibers  of  the  restiform  body  in  the  nucleus  of  the  lateral  column 
and  the  external  nucleus  of  the  column  of  Burdach. 

Ace,  external  arcuate  fibers ;  aci,  internal  arcuate  fibers ;  Crst, 
restiform  body;  Fcg,  descending  cerebellar  tract;  Fcv,  cerebellar- 
vestibular  bundles;  Fs,  solitary  bundle;  Flp,  posterior  longitudinal 
fasciculus ;  lo,  interolivary  layer ;  Lis,  an  accessory  lesion,  several  internal 
arcuate  fibers  having  been  cut;  NeB,  external  nucleus  of  the  column  of 
Burdach;  Nl,  nucleus  of  the  lateral  column;  Oi,  inferior  olive;  Py,  pyra- 
mid; Vs,  descending  root  of  the  fifth  nerve. 

Among  the  fibers  which  go  to  the  nucleus  of  Deiters,  or  which 
follow  the  uncus,  there  are  a  certain  number  which  join  from 
above,  below  and  contribute  to  form  the  cerebello-vestibular 
bundles. 

To  sum  up,  there  are  intimate  relations  between  the  nuclei  of 
the  vestibular  nerve  and  the  central  gray  nuclei  of  the  cerebellum, 


ANATOMY    OF    THE    CEREBELLUM 


35 


more  particularly  the  nucleus  of  the  tegmentum.  Since  the  nu- 
cleus of  the  tegmentum  belongs  particularly  to  the  vermis  and 
the  dentate  nucleus  depends  more  upon  the  cortex  of  the  lateral 
lobej  it  results  that  there  should  exist  between  the  vermis  and 
the  vestibular  apparatus  physiological  relations  of  the  greatest 
importance. 


Grit 


Os  .00. 


FIG.  23.  Section  designed  to  show  the  degeneration  of  the  superior 
cerebellar  peduncle  on  the  side  of  the  lesion  and  of  the  arciform  bundle 
on  the  opposite  side.  (The  section  is  not  absolutely  horizontal,  but  oblique 
from  above  downward  and  from  right  to  left.) 

Crst,  restiform  body;  Ctr,  trapezoid  body;  Fcr,  unciform  bundle; 
Floe,  flocculus ;  Flp,  posterior  longitudinal  fasciculus;  Oo-oa,  superior  olive 
and  accessory  olivary  nucleus;  Psc,  superior  cerebellar  peduncle;  Py, 
pyramid;  Rm,  median  fillet  of  Reil;  X,  zone  of  degeneration  in  the  median 
reticulate  substance;  Vpm,  small  motor  root  of  the  fifth  nerve  degenerated 
in  consequence  of  a  lesion  of  its  nucleus  of  origin;  Vs,  descending  root 
of  the  fifth  nerve. 

The  Inferior  Cerebellar  Peduncle  or  Restiform  Body. — The 
few  fibers  which  degenerate  in  the  restiform  body  of  the  same 
side  after  the  destruction  of  a  cerebellar  hemisphere,  stop  for  the 
most  part  in  the  reticular  substance  of  the  medulla,  particularly 


3O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

in  the  nucleus  of  the  lateral  segment  and  in  the  nucleus  of  v. 
Monakow  (external  nucleus  of  the  column  of  Burdach).  The 
inferior  cerebellar  peduncle,  therefore,  is  composed  almost  ex- 
clusively of  afferent  fibers. 

The  Relations  of  the  Cerebellum  and  the  Spinal  Cord. — Opin- 
ions are  very  much  divided  as  to  the  nature  of  the  relations  be- 
tween the  cerebellum  and  the  spinal  cord. 

The  central  gray  nuclei  of  the  cerebellum  send  fibers  to  the 
nuclei  of  Deiters  and  Bechterew.  The  axis  cylinder  prolonga- 


NB 


FIG.  24.  Section  of  the  medulla  passing  through  the  level  of  the 
decussation  of  the  pyramids.  Degeneration  of  the  descending  cerebellar 
tract. 

Dpy,  decussation  of  the  pyramids;  Fed,  descending  cerebellar  bundle; 
Ffa,  anterior  fundamental  bundle ;  Fmc,  funiculus  cuneatus ;  Fnc,  f uniculus 
gracilis;  NB,  nucleus  of  the  tract  of  Burdach;  NG,  nucleus  of  the  column 
of  Goll;  Nl,  nucleus  of  the  lateral  column;  Py,  pyramid. 

tions  of  the  cells  of  Deiters'  nucleus  terminate  partly  in  the 
anterior  horns,  after  having  followed  the  antero-lateral  segment 
of  the  cord.  At  the  level  of  the  medulla  they  pass  through  the 
reticular  substance  and  the  posterior  longitudinal  fasciculus. 
These  fibers  appear  to  enter  more  in  relation  with  the  antero- 
internal  groups  of  cells  than  with  the  external  and  posterior 
nuclei  of  the  anterior  horns.  They  can  be  followed  the  whole 
length  of  the  cord.  In  addition  to  these  some  fibers  leave  the 
nuclei  of  Deiters  and  of  Bechterew  and  go  to  the  oculo-motor 
nuclei,  more  particularly  to  the  nucleus  of  the  sixth  pair  of  the 
same  side  and  to  the  nucleus  of  the  third  pair  of  the  opposite 


ANATOMY    OF    THE    CEREBELLUM 


37 


side.     These  latter  follow  the  contra-lateral  posterior  longitudinal 
fasciculus  (Andre-Thomas). 

The  tonic  and  coordinating  influence  of  the  nuclei  of  the 
eighth  pair  (vestibular),  not  only  over  the  muscles  of  the  trunk 


FIG.  25.     Section  passing  through  the  level  of  the  first  cervical  root. 
Fed,  descending  cerebellar  bundle  (side  of  the  lesion). 

and  limbs  but  also  over  those  of  the  eyes,  is  deducible  from  these 
simple  anatomical  observations;  since  these  nuclei  receive  at  the 
same  time  vestibular  and  cerebellar  fibers.  One  may  conclude 
from  this  that  coordinations  of  the  same  order  may  be  presided 


FIG.  26.    The  descending  cerebellar  bundle  in  the  mid-dorsal  region. 

over  both  by  the  cerebellum  and  by  the  vestibular  nerves.  Phys- 
iological experiments  have  in  fact  shown  that  lesions  of  one  or 
the  other  produce  analogous  but  not  identical  phenomena. 


30  THE    FUNCTIONS    OF    THE    CEREBELLUM 

The  existence  of  indirect  relations  of  the  cerebellum  with  the 
spinal  cord  through  the  intermediation  of  the  nucleus  of  Deiters 
is  definitely  admitted.  This  is  not  the  case  with  the  direct  rela- 


FIG.  27.  Section  of  the  medulla  passing  through  the  trapezoid  body 
and  the  superior  olives.  The  descending  cerebellar  bundle  (Fed),  after 
having  crossed  the  nucleus  of  Dieters,  is  directed  forward  in  the  lateral 
reticular  substance  (Sir). 

Crst,  restiform  body;  Ctr,  trapezoid  body;  Fed,  descending  cerebellar 
bundle;  For,  unciform  bundle;  Floe,  flocculus;  Flp,  posterior  longitudinal 
fasciculus;  Nd,  nucleus  of  Dieters;  Ndl,  dentate  nucleus;  Os,  superior 
olive;  PCS,  superior  cerebellar  peduncle;  Py,  pyramid;  Rm,  median  fillet  of 
Reil;  Sri,  lateral  reticular  substance;  Srm,  Median  reticular  substance;  Vs, 
descending  root  of  the  fifth  nerve;  VI,  sixth  nerve;  VII,  facial  nerve; 
VIII,  v,  vestibular  nerve.  The  nucleus  of  Bechterew  is  behind  the  nucleus 
of  Dieters  between  the  restiform  body  and  the  fourth  -ventricle. 

tions.  Descending  cerebellar  fibers  are  admitted  by  Marchi, 
Andre-Thomas,  Orestano  and  Luna.  They  originate  in  the  den- 
tate nucleus.  The  path  of  this  bundle  which  I  have  indicated  in 


ANATOMY     OF     THE     CEREBELLUM 


39 


a  former  work  is  as  follows  (Figs.  27  and' 28)  :  Coining  out  of  the 
dentate  nucleus  the  descending  cerebellar  bundle  crosses  the 
nucleus  of  Bechterew  throughout  its  whole  width.  Its  fibers 
then  are  directed  towards  the  reticular  substance  of  the  pons, 
and  pass,  some  below,  some  above  and  some  between  the  fibers 
of  •  the  facial  nerve.  They  then  take  two  directions,  the  larger 


FIG.  28.    Afferent  fibers  of  the  cerebellum. 

number  going  anteriorly  in  the  lateral  part  of  the  reticular  sub- 
stance and  mingle  with  that  part  of  the  fibers  of  the  nucleus  of 
Deiters  destined  for  the  spinal  cord;  the  others  pass  posteriorly. 
The  anterior  group,  situated  at  first  behind  the  olive,  then 
behind  the  nucleus  of  the  facial  nerve,  occupies  the  antero- 
external  border  of  the  inferior  olive  lower  down.  The  posterior 
group  is  placed  in  front  of  the  genu  of  the  facial  nerve,  and  then 
in  front  of  the  triangular  nucleus  of  the  vestibular  nerve.  At 
the  lower  level  of  the  medulla,  the  two  groups  tend  to  confound 
themselves  one  with  another  and  after  decussating  form  a  bundle 


4O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

in  the  antero-lateral  segment  of  the  spinal  cord.  This  bundle 
can  be  followed  as  far  as  the  lumbar  cord.  Besides  these,  some 
fibers  pass  through  the  bundle  of  the  uncus  and  internal  segment 
of  the  restiform  body  to  descend  in  the  anterior  ground  bundle 
of  the  spinal  cord  of  the  opposite  side.  These  last  fibers  do  not 
go  below  the  mid-dorsal  region. 

The  existence  of  descending  cerebellar  fibers  is  denied  by 
Ferrier  and  Turner,  Risien  Russell,  Van  Gehuchten  and  Kohn- 
stamm.  For  these  authors  degeneration  of  the  antero-lateral 
tract  of  the  cord  following  a  destruction  of  the  cerebellum  is  not 
observed  unless  the  nucleus  of  Deiters  has  been  affected  by  the 
lesion.  Descending  cerebellar  fibers  have  not  as  yet  been  ob- 
served in  man. 

III.   Intrinsic  Fibers  of  the  Cerebellum.     Fibers  of  Projection 

and  Association.     Connections  of  the  Cerebellar  Cortex 

with  the  Central  Gray  Nuclei 

In  addition  to  the  afferent  and  efferent  fibers  there  exist  in- 
trinsic fibers,  that  is -to  say,  fibers  which  have  their  origin  and 
termination  within  the  cerebellum  itself.  These  fibers  are  of  two 
orders.  Fibers  of  projection  and  fibers  of  association.  The 
fibers  of  projection  unite  the  cerebellar  cortex  to  the  central  gray 
nuclei;  the  fibers  of  association  unite  the  lobes,  lobules  and 
lamellae  of  the  cerebellum,  one  to  another. 

Fibers  of  Projection  (Fig.  29). — The  fibers  of  projection  take 
their  origin  for  the  most  part  in  the  cerebellar  cortex  and  termi- 
nate in  the  central  gray  nuclei ;  the  dentate,  globosis,  emboliformis 
and  nucleus  of  the  tegmentum.  It  is  also  probable  that  a  number 
of  fibers  originate  in  these  nuclei  and  go  to  the  cerebellar  cortex. 
Their  existence,  however,  has  not  been  so  definitely  shown  as 
that  of  the  first  kind. 

There  is  a  systematization  in  the  cortico-nuclear  relations. 

The  dentate  nucleus  receives  fibers  from  the  cortex  of  the 
lateral  lobe  (Andre-Thomas,  Clarke  and  Horsley),  and  also  fibers 
from  the  median  lobe  of  the  vermis  (Clarke  and  Horsley).  The 
nucleus  of  the  tegmentum  receives  fibers  from  the  vermis  and 
from  the  flocculus.  According  to  Clarke  and  Horsley  the  nucleus 
of  the  tegmentum  would  receive  fibers  from  the  whole  of  the 
cerebellar  cortex.  If  this  be  true  it  would  have  an  important 


FIG.  29.     Efferent  fibers  and  fibers  of  projection  of  the  cerebellum. 

(Same  legend  for  both  cuts.) 

Cip,  posterior  segment  of  the  internal  capsule;  Cisl,  retro-lenticular 
segment  of  the  internal  capsule;  Crst,  restiform  body;  fed,  descending 
cerebellar  bundle;  FG,  tract  of  Cowers;  Floe,  flocculus;  Flp,  posterior 
longitudinal  bundle;  Ln,  locus  niger;  Na,  Ne,  Ni,  anterior,  external  and 
internal  nuclei  of  the  thalamus;  Nanc,  arciform  nucleus;  NC,  caudate 
nucleus;  NCB,  nucleus  of  the  column  of  Burdach;  NCG,  nucleus  of  the 
column  of  Goll;  ND,  Dieters'  nucleus;  Ndl,  dentate  nucleus;  Nl,  nucleus 
of  the  lateral  column;  NL-i,  Nl-2,  Nl-$,  first,  second  and  third  segments 
of  the  lenticular  nucleus;  ATM,  nucleus  of  Monakow;  Npt,  pontine  nucleus; 
NR,  red  nucleus;  Nrt,  nucleus  reticularis  tegmenti  pontis;  Nt,  nucleus  of 
the  roof  (fastigii)  ;  Oi,  inferior  olive;  P,  cerebral  peduncle  or  crus;  Py, 
pyramidal  bundle  and  pyramid;  Pci,  Pcm,  PCS,  inferior  median  and 
superior  cerebellar  peduncles ;  Sgr,  gelatinous  substance  of  Rolando ;  Th, 
thalamus;  V<\,  fourth  ventricle;  III,  nucleus  of  motor  ocularis  communis 
nerves;  V,  descending  branch  of  fifth  nerve;  VI,  nucleus  of  sixth  nerve. 


42  THE    FUNCTIONS    OF    THE    CEREBELLUM 

physiological  bearing,  especially  taking  account  of  the  intimate 
ties  which  unite  the  nucleus  of  the  roof  and  the  nuclei  of  the 
vestibular  nerve. 

The  globosus  does  not  have  any  relations  with  the  cortex  of 
the  lateral  lobe.  It  is  a  part  of  the  vermis  and  enters  into  con- 
nection principally  with  the  paramedian  lobe  (Horsley  and 
Clarke). 

No  matter  which  nucleus  is  concerned,  the  relations  with  the 
cortex  are  always  direct;  each  region  of  the  cerebellar  cortex  is 
in  relation  with  a  nucleus  or  with  nuclei  of  the  same  side.  These 
fibers  do  not  cross  the  median  plane  (Clarke  and  Horsley). 

To  sum  up,  the  fibers  of  projection  of  the  cerebellar  cortex 
are  destined  for  different  nuclei  according  to  the  region.  It  is 
to  the  nucleus  of  the  tegmentum  and  accessorily  to  the  nucleus 
globosus  that  the  fibers  of  the  vermis  are  projected.  The  fibers 
of  the  cortex  of  the  lateral  hemispheres  project  themselves  to 
the  dentate  nuclei. 

On  the  other  hand  the  vermis  receives  fibers  from  the  medulla 
and  from  the  spinal  cord.  The  lateral  hemisphere  receives  fibers 
from  the  middle  cerebellar  peduncle  which  unites  it  with  the 
cerebral  cortex.  Clarke  and  Horsley  are  therefore  correct  in 
basing  their  conclusions  upon  these  anatomical  considerations, 
when  they  distinguish  two  systems  in  the  cerebellar  cortex:  a 
spino-cerebellar  system,  and  a  cerebro-cerebellar  system.  The 
same  authors  note  also  that  as  auditory  sensations  are  located  in 
the  temporal  lobe,  that  the  sensations  of  equilibrium  and  orienta- 
tion which  are  dependent  upon  the  vestibular  nerve,  should  have 
their  seat  in  the  same  neighborhood.  These  last  are  localized  by 
Mills  in  the  posterior  third  of  the  temporal  lobe  (second  and  third 
convolutions).  As  I  have  already  remarked  it  is  precisely  in 
this  region,  or  adjacent  regions,  that  the  bundle  of  Tiirck  (exter- 
nal bundle  of  the  central  peduncle)  takes  its  origin.  This  bundle 
goes  to  the  nuclei  of  the  pons,  which  are  the  origin  of  the  middle 
cerebellar  peduncle. 

Thus  crossed  relations  are  established  between  the  temporal 
lobe,  the  center  of  labyrinthine  representations,  and  the  lateral 
lobe  of  the  cerebellum.  Clarke  and  Horsley  insist  upon  the 
physiological  importance  of  this  fact. 

Fibers  of  Association. — The  paths  and  extent  of  these  fibers 


ANATOMY    OF    THE    CEREBELLUM  43 

have  been  particularly  well  studied  by  Clarke  and  Horsley  by  the 
method  of  secondary  degeneration.  Their  conclusions  are  as 
follows :  Some  fibers  pass  from  the  vermis  to  the  lateral  lobes, 
but  never  beyond  the  plane  of  the  paramedian  lobe  (cat,  dog  and 
monkey),  some  arciform  association  fibers  take  a  lateral  path  as 
far  as  the  second  lamella  from  the  edge  of  the  lesion,  rarely  as 
far  as  the  third.  Extensive  lesions  of  the  vermis,  and  particu- 
larly those  of  the  median  lobe,  are  followed  by  extensive  degen- 
erations of  arciform  fibers  which  follow  an  antero-posterior  path 
and  are  contained  therefore  in  the  vermis.  The  fibers  which  go 
to  the  nodule  are  very  few. 

These  experiments  have  shown  the  almost  complete  indepen- 
dence of  the  vermis  and  the  lateral  hemispheres.  There  are  no 
commissural  fibers  between  the  two  lateral  parts  of  the  cere- 
bellum. The  same  authors  furnish  some  information  as  to  the 
caliber  of  the  different  systems  of  fibers.  The  fibers  of  projec- 
tion, or  cortico-nuclear,  are  fine,  or  medium-sized  fibers.  The 
arciform  fibers,  or  fibers  of  association,  are  fine  fibers.  As  to 
the  nucleo-peduncular  fibers,  the  superior  ones  are  large;  the 
intermediate  fine;  and  the  inferior  ones  of  medium  caliber. 

IV.    Embryological  Significance  of  the  Cerebellum 

At  the  commencement  of  the  second  month  of  the  life  of  the 
embryo  two  grooves  are  seen  upon  the  lateral  walls  of  the  human 
spinal  cord,  two  lateral  grooves  which  divide  each  lateral  side  into 
two  halves ;  the  anterior  or  fundamental  fold  of  His  and  the 
posterior  or  alar  fold.  The  fundamental  fold  and  the  alar  fold 
are  united  by  a  lozenge-shaped  intermediary  portion.  It  is  at 
the  expense  of  the  fundamental  fold  that  the  anterior  gray  com- 
missure, the  anterior  white  commissure,  the  anterior  cornu,  the 
anterior  tracts,  the  anterior  part  of  the  lateral  tracts,  and  the 
anterior  half  of  the  arcuate  formation  are  formed;  they  enclose 
all  the  nuclei  of  origin  of  the  motor  nerves. 

The  intermediate  part  forms  the  neck  of  the  posterior  cornu  ; 
the  column  of  Clarke,  the  reticular  process  and  the  posterior  part 
of  the  lateral  tract  (crossed  pyramidal  tract  and  the  direct  cere- 
bellar  tract  of  Flechsig).  The  posterior  part,  or  alar  fold  forms 
the  posterior  cornu,  and  the  posterior  cord,  and  receives  the  roots 
of  the  sensory  nerves.  At  the  level  of  the  medulla,  as  in  the 


44  THE    FUNCTIONS    OF    THE    CEREBELLUM 

spinal  column,  the  fundamental  fold  gives  rise  to  the  motor 
nerves.  The  alar  fold  receives  the  termination  of  the  medullary 
sensory  nerves. 

The  alar  fold  then  divides  into  two  segments :  the  one  internal 
or  jugal,  and  the  other  external  or  rhomboidal  lip  of  His.  The 
jugal  segment  becomes  later  on,  first,  in  the  medullary  regions, 
the  nucleus  of  the  tract  of  Goll,  the  gray  wing,  the  acoustic  tuber- 
cle; and  second,  in  the  pontine  region,  the  locus  coeruleus. 

The  rhomboidal  lip  forms  in  its  turn  first,  in  the  medullary 
region,  the  medullary  or  inferior  olive,  the  accessory  olivary 
nuclei,  the  nucleus  of  the  tract  of  Burdach,  the  nuclei  of  the  lat- 
eral tracts,  the  arcuate  nuclei  of  the  pyramids,  and  the  gelatinous 
substance  of  Rolando.  The  fibers  which  arise  from  them  will 
form  the  internal  arcuate  fibers  of  the  medulla,  the  system  of 
olivary  fibers,  the  trapezoid  body,  the  interolivary  layer  and  the 
restiform  body.  Second,  in  the  pontine  region  the  pontine  olive, 
the  gelatinous  substance  of  Rolando,  the  internal  arcuate  fibers, 
the  trapezoid  body  and  the  fold  of  the  cerebellum  (J.  and  A. 
Dejerine). 

The  cerebellum,  therefore,  is  developed  along  the  path  of  the 
sensory  tracts,  and  as  an  accessory  of  the  sensory  tract.  At  first 
it  is  a  double  organ,  the  two  parts  of  which  unite  afterwards  in 
the  median  line.  The  cerebellar  fold  first  develops  the  vermis  in 
its  median  portion ;  it  is  there  that  the  first  grooves  to  the  num- 
ber of  three  or  four  appear  towards  the  third  month  of  intra- 
uterine  life.  The  grooves  of  the  cerebellar  hemispheres  appear 
during  the  fourth  month.  The  cerebellum  does  not  acquire  its 
final  form  until  about  the  fifth  month.  The  fibers  of  the  vermis 
myelinate  much  earlier  than  those  in  the  hemispheres. 

V.    Comparative  Anatomy 

The  cerebellum  follows  a  course  in  its  development  in  the 
animal  series  parallel  to  that  of  the  nervous  system  in  general. 
Rudimentary  in  fishes  it  acquires  its  maximum  of  development  in 
mammals. 

The  cerebellum  of  fishes  is  situated  behind  the  optic  lobes 
and  consists  of  an  elongated  appendix,  adherent  by  its  base  in 
front,  and  free  behind,  implanted  upon  the  sides  of  the  spinal 
cord.  The  superior  face  is  traversed  by  an  antero-posterior 
groove. 


ANATOMY     OF     THE     CEREBELLUM 


45 


The  surface  is  smooth  in  the  bony  fishes ;  in  the  cartilaginous 
fishes  it  is  divided  by  grooves  into  lamellae  analogous  to  those 
in  the  superior  vertebrates.  The  division  into  lamellae  is  found 
in  sharks  and  fish  of  the  same  order.  In  the  sturgeon  family 
the  cerebellum  is  represented  only  by  a  little  ball  of  fat. 

Edinger  remarks  that  the  Myxine,  a  worm-like  fish  which 
lives  within  the  bodies  of  other  fish  as  a  sort  of  parasite,  or  on 
rocks  where  it  fixes  itself,  has  no  cerebellum.  The  flat  fish  which 
lives  in  the  sand  has  a  cerebellum  much  less  developed  than  other 
fish  of  the  same  family. 


30  31 

FIG.  30.  Section  of  the  medulla  and  the  cerebellum  of  a  snake 
(morelia  argus).  It  is  reduced  to  a  simple  transverse  fold.  (Stained  by 
the  method  of  Pal.) 

FIG.  31.     The  encephalon  of  a  crane.     The  cerebellum,  seen  in  profile,  is 
represented  by  a  voluminous  vermis  and  a  very  small  lateral  appendix. 

The  cerebellum  of  reptiles  is  reduced  to  a  simple  transverse 
fold  placed  across  the  fourth  ventricle,  viz.,  toads,  frogs,  lizards, 
vipers,  etc.  (Fig.  30).  The  cerebellum  is  wanting  in  the  sala- 
mander which  lives  under  the  ground.  In  the  tortoise  it  has  a 
globular  form  and  its  volume  is  greater  than  that  of  the  optic 
lobe.  In  the  turtle  the  cerebellum  is  twice  as  large  as  it  is  in  the 
tortoise  (Edinger)  ;  according  to  this  author,  this  is  due  appar- 
ently to  the  great  activity  which  the  animal  displays  in  swimming. 
The  cerebellum  of  the  crocodile  is  folded  upon  itself  several 
times  and  possesses  two  lateral  appendices. 

In  birds  the  cerebellum  takes  on  a  much  greater  development ; 
even  when  compared  with  the  whole  encephalic  mass  (Fig.  31). 
In  spite  of  this  it  is  formed  almost  entirely  by  the  median  lobe 
composed  of  transverse  lamellae  varying  in  number  from  ten  to 


k 


46  THE    FUNCTIONS    OF    THE    CEREBELLUM 

twenty,  according  to  Leurat.  In  some  birds  the  cerebellum  is 
provided  with  two  small  lateral  appendices,  the  first  appearance 
of  the  lateral  lobes  of  the  mammals.  The  lateral  appendices  are 
scarcely  visible  in  the  chicken,  the  goose,  the  thrush  and  the  spar- 
row. They  are  observable  in  the  partridge,  the  pigeon,  the 
ostrich,  the  duck,  and  the  crane.  The  birds  which  rise  and  sus- 
tain themselves  in  the  air  like  the  cranes,  and  those  whose  wings 
and  legs  have  considerable  power, as  the  loon  (of  Bassan),andthe 
parrots,  have  their  lateral  appendices  more  developed  (Serres). 
The  grooves  and  the  folds  are  developed  proportionately  to  the 
size  of  the  birds.  Comparing  the  weight  of  the  cerebellum  in 
different  species  of  birds,  Lapicque  and  Girard  conclude  that  it 
seems  related  to  certain  functional  attitudes.  The  development 
of  the  cerebellum  would  seem  remarkable  in  birds  of  prey  and  in 
sea  birds.  A  comparison  with  the  pigeon  and  the  snipe  would 
seem  to  indicate  an  especial  relation  with  soaring;  this  is  prac- 
tically the  same  opinion  formerly  expressed  by  Serres.  The  cere- 
bellum of  birds  contains  equally  two  organs;  the  cortex  and  the 
central  gray  nuclei.  The  central  gray  nuclei  are  four  in  number : 
two  median  and  two  lateral  (Brandis).  Besides  these  the  bridge 
of  nerve  substance  which  joins  each  side  of  the  vermis  to  the 
continuation  of  the  spinal  cord  contains  a  nucleus  which  is  in 
immediate  juxtaposition  to  the  lateral  nucleus  of  the  cerebellum, 
and  which  belongs  to  the  nuclear  apparatus  of  the  eighth  pair 
(Fig.  32). 

The  experimental  researches  of  Frenkel  on  the  pigeon  permit 
us  to  establish  the  existence  of  a  certain  number  of  systems  of 
fibers  which  present  some  analogy  with  those  in  mammals.  The 
afferent  fibers  come  from  the  base  of  the  posterior  cornu  of  the 
spinal  cord,  from  the  nuclei  of  the  posterior  columns,  and  from 
those  of  the  corpora  bigemini.  The  majority  of  them  terminate 
in  the  cortex.  The  nuclear  contingent  is  very  scant.  The  fibers 
which  come  from  the  cerebellar  cortex  form  the  commissural 
fibers  and  the  fibers  of  association,  in  addition  to  the  fibers  of 
projection  which  go  to  the  central  nuclei.  Some  fibers  attain  the 
nuclei  of  the  vestibular  nerve.  The  greater  number  of  the  effer- 
ent fibers  take  their  origin  in  the  median  and  lateral  nuclei,  and 
are  destined  for  the  nuclei  of  the  vestibular  nerve  (in  birds,  as 
well  as  in  mammals  the  relations  of  the  cerebellum  and  the  nuclei 


ANATOMY    OF    THE    CEREBELLUM  47, 

of  the  vestibular  nerve  are  very  intimate),  to 'the  motor  nuclei  of 
the  fifth  nerve,  and  of  the  facial  nerve,  as  weir  as  to  the  motor 
nuclei  of  the  spinal  cord.  These  fibers  occupy  the  lateral  tract, 


FIG.  32.     Transverse  section  of  the  cerebellum  and  medulla  of  a  pigeon 
(Weigert-Pal  staining),  intended  to  show  the  central  gray  nuclei. 
Na,  anterior  nucleus ;  A7/?,  posterior  nucleus  and  its  relations  with  the 

eighth  nerve  (VIIIv};  Scv,  cerebello-vestibular  bundles;  NB,  nucleus  of 

Bechterew. 

and  are  partly  direct  and  partly  crossed,  to  the  olivary  nuclei  of 
the  prolongation  of  the  spinal  cord,  to  the  posterior  longitudinal 
fasciculus  which  they  follow  to  terminate  in  the  oculo-motor 


48 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


nuclei,  and  in  the  spinal  cord  (anterior  bundle),  to  the  red  nucleus 
of  the  opposite  side  and  to  the  optic  thalamus. 


The  lateral  appendices  of  the  cerebellum  of  birds  takes  on  a 
much  greater  development  in  mammals  and  become  the  lateral 
lobes.  The  number  of  lobules  and  lamellae  increases  with  the 


ANATOMY     OF     THE     CEREBELLUM 


49 


height  and  weight.  The  relation  of  the  median  lobe  to  the  hemi- 
spheres varies  according  to  the  different  species.  The  median 
lobe  is  very  large  in  the  rodents,  it  is  much  smaller  in  the  rumi- 
nants, the  solipedes  and  carnivoras.  The  progressive  growth  of 
the  hemispheres  is  still  more  marked  in  the  monkeys  and  apes 
(Figs.  33  and  34),  and  attains  its  maximum  in  man.  It  seems 


FIG.  34.  Vertico-transverse  section  of  the  pons  and  the  cerebellum  of 
a  chimpanzee  (Weigert-Pal)  to  show  the  considerable  development  of  the 
anterior  stage  of  the  pons,  the  cerebellar  hemispheres  and  the  cerebellar 
olives  (Oc). 

V ,  vermis ;  Am,  amygdalae.     Enlargement  2. 

subordinated  to  that  of  the  cerebrum.  The  importance  of  the  pons 
and  the  middle  cerebellar  peduncle  is  accentuated  in  the  same 
way.  In  the  anthropoid  apes  the  anterior  surface  of  the  pons 
increases  considerably  in  size,  at  the  same  time  with  the  middle 
cerebellar  peduncle  and  the  lateral  lobe  (Fig.  34). 
5 


5O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

In  mammals,  as  a  study  of  secondary  degeneration  proves, 
there  are  intimate  relations  between  the  central  gray  nuclei  of  the 
cerebellum  and  the  nuclei  of  the  vestibular  nerve.  In  all  mam- 
mals except  man  the  nucleus  of  Bechterew  is  continued  as  far 
as 'the  nucleus  of  the  tegmentum,  under  the  form  of  little  bridges 


FIG.  35.  Photograph  of  a  transverse  section  of  the  medulla  and  the 
nuclei  of  the  cerebellum  of  a  dog  (stain  Weigert-Pal).  Relations  of  the 
nuclei  of  the  cerebellum  with  the  nuclei  of  the  vestibular  nerve  by  means 
of  the  internal  semicircular  fibers  (Fsmi). 

Floe,  flocculus ;  Flp,  posterior  longitudinal  fasciculus ;  CvVlll,  ventral 
nucleus  of  the  auditory  nerve;  GVll,  genu  of  the  facial;  NB,  nucleus  of 
Bechterew;  MD,  nucleus  of  Deiters;  Nt,  nucleus  of  the  roof;  Nl,  lateral 
nucleus ;  Nla,  antero-lateral  nucleus ;  Os,  superior  olive ;  Py,  pyramid ; 
VII,  facial;  VIIIv,  vestibular  nerve. 

o'f  gray  substance  intercalated  between  the  tracts  which  go  from 
the  vermis  to  the  prolongation  of  the  spinal  cord  (Weidenreich). 
This  is  the  same  anatomical  disposition  that  has  been  described 
by  Brandis  in  birds.  In  consequence  of  this  disposition  of  ana- 
tomical connections,  which  unites  the  nucleus  of  Bechterew  with 


ANATOMY    OF    THE    CEREBELLUM  5! 

the  cerebellum,  this  nucleus  can  just  as  well  be  considered  a  cere- 
bellar nucleus  as  a  vestibular  nucleus. 

It  is  only  in  the  highest  mammals  such  as  the  superior  apes 
and  man,  by  reason  of  the  considerable  development  of  the  cortex 
of  the  lateral  lobes,  that  the  rhomboid  body  or  cerebellar  olive 
takes  on  the  folded  appearance  which  has  given  it  the  name  of 
the  dentate  nucleus.  In  all  mammals  four  central  gray  nuclei 
can  be  distinguished :  the  median  nucleus,  the  antero-lateral  nu- 
cleus, the  postero-lateral  nucleus  and  the  lateral  nucleus  (Fig. 
35).  The  median  nucleus  corresponds  to  the  nucleus  fastigii, 
or  nucleus  of  the  tegmentum,  in  man.  The  antero-lateral  nucleus 
to  the  emboliformis,  the  postero-lateral  nucleus  to  the  globulus, 
and  the  lateral  nucleus  to  the  dentate  nucleus. 


FIG.  36.  Cerebellum  of  a  dog.  Superior  surface.  (Nomenclature  of  Bolk.) 
Fv,  vermicular  formation  of  petrous  lobe;  La,  anterior  lobe;  Lam, 
auriform  lobe;  C-i,  crus  primum;  C-2,  crus  secundum;  Lmp,  posterior 
median  lobe;  Lp,  paramedian  lobe;  Ls,  lobus  simplex;  Si,  primary  groove; 
Sp,  paramedian  groove. 

Of  late  Bolk  has  contributed  some  important  work  on  the 
comparative  anatomy  of  the  cerebellum,  in  an  effort  to  establish 
a  parallel  between  the  degree  of  development  of  this  or  that  part 
of  the  cerebellum,  and  the  synergy,  or  greater  or  less  individuali- 
zation  of  the  movements  of  the  anterior  and  posterior  limbs.  He 
has  thus  denned  cerebellar  cortical  localizations  for  the  anterior 
limbs,  the  posterior  limbs,  the  head  and  the  trunk.  Bolk  combats 


52  THE    FUNCTIONS    OF    THE    CEREBELLUM 

the  classic  opinion  according  to  which  the  cerebellum  is  divided 
into  a  median  lobe  or  vermis,  and  into  cerebellar  hemispheres. 
He  considers  the  cerebellum  of  all  mammals  to  have  two  lobes : 
the  anterior  lobe  and  the  posterior  lobe,  separated  by  the  primary 
groove  (Fig.  36). 

The  anterior  lobe  is  formed  of  transverse  juxtaposed  lamellae. 

The  posterior  lobe  is  divided  into  two  parts,  anterior  and 
posterior.  The  anterior  or  lobule  simplex  is  slightly  developed  and 


FIG.  37. 


Sigittal  section  of  the  vermis   (man), 
nomenclature  of  Bolk.) 


(Application  of  the 


formed,  like  the  anterior  lobe,  of  transverse  lamellae.  The  poste- 
rior part  is  composed  of  a  median  lobule  and  two  lateral  lobules. 
The  median  lobule,  small  and  limited  on  each  side  by  the  para- 
median  groove,  is  subdivided  into  three  parts,  anterior,  median 
and  posterior.  In  each  lateral  lobule  Bolk  distinguishes  three 


ANATOMY     OF    THE     CEREBELLUM  53 

parts,  the  ansiform  lobe,  divided  into  two  arms,  the  anterior  and 
posterior  by  the  intercrural  groove,  the  para-median  lobule  and 
the  vermicular  formation  of  the  petrous  lobe.  This  disposition 
is  especially  well  shown  in  the  cerebellum  of  the  dog.  The  ante- 
rior lobe  corresponds  in  man  to  the  central  lobe,  the  culmen,  and 
anterior  quadrilateral  lobe.  The  lobule  simplex  to  the  declive 
and  to  the  posterior  quadrilateral  lobe  (Fig.  37).  In  these  forma- 
tions there  is  no  necessity  to  distinguish  a  vermian  and  a  hemi- 
spheric portion;  each  lobe  is  considered  as  a  whole. 

In  the  posterior  part  of  the  posterior  lobe,  the  ansiform  lobe, 
which  in  man  takes  on  a  very  great  development,  is  the  equivalent 
of  the  superior  semilunar  lobe,  of  the  inferior  semilunar  lobe,  of 
the  lobus  gracilis,  and  of  the  digastric  lobes  all  together.  The 
paramedian  lobe  becomes  the  amygdalus,  and  the  vermicular  lobe, 
the  flocculus.  In  each  kind  of  mammal,  each  of  these  parts 
takes  on  more  or  less  importance  in  relation  to  the  others,  accord- 
ing to  greater  or  lesser  development  of  this  or  that  group  of  mus- 
cles. The  muscular  groups  of  median  organs  with  synergic  func- 
tions have  their  seat  in  the  median  part  of  the  cerebellum,  in  the 
same  way  that  the  centers  of  coordination  of  the  lateral  groups 
of  muscles  have  their  seat  in  the  lateral  parts  of  the  cerebellum, 
where  this  function  is  independent  of  homologous  groups  of  the 
same  side. 

The  anterior  lobe  is  the  center  for  all  the  muscles  of  the  head. 
The  lobule  simplex  is  the  center  for  the  muscles  of  the  neck. 
The  posterior  part  of  the  median  lobe  contains  the  centers  of  the 
synergic  movements  of  the  upper  and  lower  limbs.  The  ansi- 
form lobule,  the  independent  centers  of  the  upper  and  lower 
limbs.  This  is  why  the  median  lobe  is  developed  in  animals 
where  the  muscular  work  necessitates  the  synergy  of  movements 
of  the  upper  and  lower  limbs.  In  man  where  the  movements  of 
the  limbs  have  attained  their  maximum  of  individualization,  the 
anciform  lobe  attains  also  its  maximum  of  development. 

The  tonsil  or  amygdalus  and  the  pyramid  appear  to  be  the 
centers  of  the  movements  of  the  trunk;  the  flocculus  that  of  the 
movements  of  the  tail. 


CHAPTER  II 

EXPERIMENTATION.— DESTRUCTION   OF  THE  CEREBELLUM 
PARTIAL  OR  TOTAL  DESTRUCTION  OF  THE  CEREBELLUM  IN  THE  DOG 

The  phenomena  observed  in  the  dog  will  be  taken  as  examples 
and  described  first.  I  will  pay  particular  attention  to  the  results 
of  my  own  experiments  without,  however,  neglecting  the  obser- 
vations made  by  other  physiologists  who  have  occupied  them- 
selves with  this  question.  The  variations  observed  according  to 
the  different  kinds  of  animals  will  then  be  taken  up  with  a  special 
note  for  the  effects  of  the  destruction  of  the  cerebellum  in  the 
monkey. 

I.   Destruction  of  a  Lateral  Lobe  and  the  Corresponding  Half 

of  the  Vermis 

(Fig.  38) 

Immediate  Phenomena. — Most  of  the  animals  having  been 
operated  upon  in  narcosis  (ether,  chloroform,  chloral,  or  mor- 
phine), the  phenomena  described  under  this  heading  should  not 
be  confounded  with  the  phenomena  which  would  be  produced  at 
the  moment  of  destruction  if  the  animal  were  not  anesthetized. 
The  immediate  phenomena  which  are  about  to  be  described  are 
those  which  manifest  themselves  when  the  animal  comes  out  of 
the  phase  of  narcosis  and  begins  to  awake. 

The  animal  moves  little  by  little  and  emits  plaintive  whines. 
The  body  is  shaken  by  a  general  trembling,  more  apparent  in  the 
muscles  of  the  back.  It  tends  to  place  itself  in  opisthotonos,  the 
head  is  bent  backwards,  the  anterior  extremities  are  in  tonic 
extension.  When  from  time  to  time  the  animal  attempts  to  make 
some  movements,  the  tonic  contraction  of  the  members  in  exten- 
sion increases. 

When  the  animal  has  completely  awakened,  to  these  phenom- 
ena are  added  others,  which  follow  one  another,  particularly  when 
the  body  is  not  supported  on  the  operated  side.  These  are  move- 

54 


EXPERIMENTATION 


55 


ments  of  rotation  or  rolling  around  the  longitudinal  axis.  To 
observe  these  phenomena  the  animal  must  be  taken  from  his  cage 
and  placed  on  the  ground  with  his  belly  to  the  earth;  the  body 
then  describes  a  curve  with  the  concavity  towards  the  operated 
side,  and  rests  upon  this  side.  This  scoliosis  is  still  more  mani- 
fest if  one  hold  the  animal  up  by  taking  hold  of  the  loose  skin 
at  the  back.  The  head  is  turned  in  the  same  direction  but  it 
describes  at  the  same  time  a  movement  of  torsion,  so  that  the 
back  of  the  neck  is  directed  very  much  downwards  and  behind 


FIG.  38.     Destruction  of  half  of  the  cerebellum. 

on  the  operated  side,  whereas  the  muzzle  is  turned  in  the  opposite 
direction.  The  eye  of  the  side  operated  upon  looks  inward  and 
downward,  whereas  the  other  looks  upwards  and  outwards.  Both 
eyes  are  affected  by  nystagmic  movements,  which  disappear,  how- 
ever, in  a  few  days.  This  exaggerated  movement  of  torsion  of 
the  head  and  of  the  neck  is  the  beginning  of  the  gyratory  move- 
ment; the  anterior  half  of  the  trunk  then  follows  the  movement 
of  the  head  and  the  posterior  half  of  the  trunk  is  the  last  to  turn 

(Fig.  39)- 

The  animal  thus  turns  over  one  or  more  times.     These  move- 
ments reappear  spontaneously  but  there  is  no  doubt  that  they  are 


56  THE    FUNCTIONS    OF    THE    CEREBELLUM 

renewed  with  greater  frequency  under  the  influence  of  periph- 
eral or  sensory  excitations,  among  which  auditory  sensations 
appear  to  be  the  most  effective.  These  movements  of  rotation 
are  of  short  duration,  and  hardly  recur  at  all  after  the  lapse  of 
two  or  three  days.  The  direction  of  the  rotation  is  determined 
by  the  side  upon  which  the  animal  falls,  when  he  is  placed  on  his 
four  feet ;  as  he  always  falls  towards  the  operated  side,  one  may 
say  that  the  rotation  takes  place  from  the  healthy  side  towards 
the  operated  side. 


FIG.  39.  Semi-schematic.  Movement  of  rotation  around  the  longi- 
tudinal axis  from  left  to  right  which  is  observed  after  the  destruction  of 
the  right  cerebellar  hemisphere  along  or  associated  with  the  destruction  of 
the  labyrinthine  root  of  the  same  side.  « 

In  repose  during  the  first  days  that  follow  the  operation,  the 
animal  is  contracted,  he  rests  lying  on  the  operated  side  with  the 
head  in  extension  and  turned  backwards  towards  the  side  of  the 
lesion.  The  limbs  are  in  extension,  particularly  the  anterior  ones. 
As  regards  the  anterior  limbs,  as  well  as  the  posterior,  those  of 


FIG.  40.    Attitude  of  a  dog  after  the  left  half  of  the  cerebellum 
has  been  destroyed. 

the  operated  side  are  the  more  contracted.  The  head  is  some- 
times twisted  so  that  the  back  of  the  neck  looks  downwards  and 
backwards  towards  the  operated  side ;  the  muzzle  is  then  directed 
towards  the  healthy  side.  There  is  a  conjugate  deviation  of  the 
eyes  toward  the  same  side.  The  animal  cannot  lie  down  except 


EXPERIMENTATION  57 

on  the  operated  side,  or  in  a  semicircle  (Fig.  40).  The  curvature 
looking  towards  the  operated  side,  the  head  lying  upon  the  ground. 
When  the  animal  is  held  up  by  the  skin  of  his  back  the  lateral  curva- 
ture of  the  trunk  increases  (pleurothotonos),  and  half  of  the  body, 
the  operated  half,  rests  always  on  an  inferior  plane  to  that  of  the 
healthy  side.  The  anterior  and  posterior  limbs  are  contracted  in 
extension  with  a  marked  predominance  on  the  operated  side,  and 
approach  one  another  in  consequence  of  this  incurvation. 

Phase  of  Reeducation  or  Restoration.  Later  Phenomena. — 
The  pleurothotonos  persists  during  several  days,  as  does  the  ex- 
tension of  the  limbs;  up  until  the  fifth  day  according  to  Lewan- 
dowsky.  The  animal  attempts  to  lie  upon  his  stomach,  but  in 
vain;  he  falls  back  almost  immediately  upon  the  operated  side; 
it  also  attempts  to  make  some  movements,  but  always  without 
success.  Painful  excitations  provoke  incoordinated  movements, 
more  marked  in  the  limbs  of  the  healthy  side. 

In  the  abdominal  decubitus,  when  the  animal  succeeds  in  tak- 
ing and  maintaining  this  attitude,  which  he  is  not,  as  a  rule,  able 
to  do  for  several  days,  the  front  legs  are  in  marked  abduction 
and  the  one  on  the  operated  side  always  more  than  the  one  on 
the  healthy  side.  When  it  is  able  to  lift  its  head  from  the  ground, 
it  describes  lateral  oscillations  of  increasing  amplitude  which 
cause  the  animal  to  fall  again  upon  the  operated  side. 

When  the  abdominal  decubitus  can  be  maintained  for  a  few 
instants  the  animal  tries  to  rise  upon  its  four  legs.  At  first  it 
raises  the  anterior  half  of  the  body,  resting  upon  the  two  front 
legs.  Tremor  and  oscillations  of  the  head  and  of  the  trunk  imme- 
diately appear  and  result  in  a  fall,  always  on  the  operated  side. 

Three  or  four  days  after  the  first  attempts,  when  the  equi- 
librium can  be  maintained  for  a  certain  time  seated  with  the  fore 
paws  stretched  wide  apart,  the  dog  makes  some  attempts  to  walk. 
One  fore  paw,  nearly  always  the  one  of  the  operated  side,  is 
suddenly  lifted  from  the  ground  as  in  walking,  but  the  body 
immediately  collapses  on  the  operated  side,  a  fall  is  inevitable; 
or  this  movement  is  repeated  several  times  without  effect,  since 
the  posterior  portion  of  the  body  is  immobile  and  fixed  to  the 
ground,  and  prevents  progression.  Nevertheless,  the  animal  some- 
times succeeds  in  advancing  a  few  inches,  dragging  the  rest  of 
the  body,  which  slides  along  on  the  rump  of  the  opposite  side. 


5o  THE    FUNCTIONS    OF    THE    CEREBELLUM 

At  the  end  of  a  few  steps,  however,  the  fore  paw  of  the  operated' 
side  doubles  up  under  the  body  and  the  animal  falls  on  this  side. 
In  all  these  movements  the  fore  paw  of  the  injured  side  appears 
feebler  and  less  mobile  than  that  of  the  healthy  side.  At  rest 
during  abdominal  decubitus  it  is  nearly  always  in  supination. 
Many  more  days  are  necessary  before  the  animal  can  pass  from 
this  imperfect  position  to  a  position  on  its  four  paws;  before  it 
succeeds  there  are  numerous  attempts.  The  front  legs  always 
being  in  abduction,  the  posterior  portion  of  the  body  is  at  first 
only  half  sustained,  and  more  on  the  healthy  side  than  on  the 
operated  side,  where  the  rump  is  nearer  the  ground.  As  soon  as 
a  fore  paw  is  lifted,  the  body  falls  down.  Little  by  little,  the 


FIG.  41.    The  same  dog  at  the  moment  of  a  fall,  the  left  fore  paw  being 
put  suddenly  in  adduction.     (After  a  photograph.) 

posterior  half  of  the  body  is  lifted  higher  above  the  ground,  but 
for  a  long  time,  for  several  weeks  even,  it  is  upon  an  inferior 
plane  to  the  anterior  half  of  the  body. 

Fifteen  days  after  the  operation,  equilibrium  can  be  main- 
tained on  the  four  paws  for  a  short  time,  after  which  the  tremor 
and  oscillations  of  the  trunk,  either  antero-posterior  or  transverse, 
reappear  and  entail  a  fall.  The  fall  is  still  inevitable  if  one  paw 
leaves  the  ground.  Fatigue  rapidly  supervenes.  During  the  posi- 
tion on  the  four  paws  it  is  not  uncommon  that  the  front  legs 
separate  as  if  the  paws  slipped  on  the  ground. 

It  is  from  this  moment  that  the  animal  makes  serious  efforts 
to  walk.  The  anterior  paws  are  wider  apart  than  in  normal 
standing.  The  one  of  the  operated  side  is  the  more  in  abduction, 
and  is  usually  the  first  to  be  lifted.  Before  leaving  the  ground 


EXPERIMENTATION 


59 


it  is  the  seat  of  contractions  without  effect,  as  if  the  animal  hesi- 
tated. Then,  suddenly,  it  leaves  the  ground.  At  the  same  time 
the  whole  body  follows  the  movement  and  is  laterally  displaced 
towards  the  same  side,  as  if  animated  by  an  irresistible  move- 
ment of  translation.  The  animal  attempts  to  oppose  this  by  some 
movements  of  the  vertebral  column  in  the  inverse  direction,  but 
in  vain ;  the  posterior  half  of  the  body  bends  towards  the  operated 
side,  and  the  fore  paw  at  first  in  abduction  comes  suddenly  back 
to  adduction,  and  the  animal  tumbles  in  a  heap  to  this  side  (Fig. 
41).  This  is  why,  in  these  first  attempts,  the  dog  seeks  a  wall  or 
some  other  obstacle  to  lean  the  operated  side  against. 


FIG.  42.  Diagram  of  the  walk  of  a  dog  deprived  of  the  left  half  of 
the  cerebellum.  Fore  paws  in  gray,  hind  paws  in  black.  To  the  left  fore 
paws  placed  in  normal  position.  Below  diagram  of  normal  walk. 

Gradually  the  displacements  of  the  body  become  of  lesser 
amplitude  and  the  resistance  to  the  movements  of  translation 
towards  the  operated  side  is  prompter  and  more  effective.  The 
posterior  half  of  the  body  raises  itself  higher  from  the  ground. 
During  the  progress  of  walking  the  trunk  is  displaced,  first  to 
one  side  and  then  to  the  other  (Fig.  42),  each  limb  is  lifted  only 
after  some  hesitation.  In  the  interval  between  the  steps,  waver- 
ing is  constant,  the  gait  resembles  that  of  a  drunken  person, 
whence  the  name,  "  drunken  gait." 

From  now  on  there  is  a  marked  improvement  daily ;  wavering 
progressively  diminishes,  and  the  oscillations  of  the  body  and  the 
head  become  slighter.  On  the  other  hand,  the  body  no  longer 
has  the  suppleness  it  had  before  the  operation.  It  is  as  if  it  were 
ankylosed ;  the  head  is  held  stiffly,  always  inclined  towards  the 


6O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

side  of  the  lesion;  the  paws  are  not  lifted  with  the  same  regu- 
larity nor  at  the  right  time,  and  the  limbs  of  the  operated  side  are 
lifted  suddenly  and  replaced  with  equal  brusqueness. 

•  After  re-learning  to  walk,  the  dog  learns  t  o  run  again. 
During  this  reeducation,  phenomena  of  the  same  type  are  repro- 
duced, but  of  a  lesser  intensity.  The  body  does  not  follow  a 
straight  line,  but  sways  excessively,  either  to  one  side  or  to  the 
other.  The  limbs  of  the  operated  side  are  still  lifted  too  sud- 
denly and  too  high.  The  total  of  the  movements  is  lacking  in 
harmony,  whereas,  in  a  normal  dog  running  one  fore  paw  is  lifted 
almost  at  the  same  time  as  the  hind  paw  of  the  other  side,  in  the 
dog  deprived  of  half  of  his  cerebellum  this  simultaneity  is  not 
so  perfect. 

On  stopping,  the  tremors,  oscillations  and  displacements  of 
the  body  reappear.  The  same  thing  happens  every  time  there  is 
a  modification  in  the  conditions  of  equilibrium,  or  a  change  of 
position. 

During  the  first  days  the  dog  can  neither  eat  nor  drink  by 
himself,  he  cannot  seize  meat  which  is  presented  to  him,  and 
he  cannot  drink  unless  one  holds  his  head,  then  he  laps  like  a 
normal  dog.  Even  several  days  later  he  is  not  able  to  seize  food 
with  his  mouth ;  as  soon  as  he  advances  or  lowers  his  head,  wide 
oscillations,  at  first  localized  in  the  head,  pull  it  from  one  side  to 
the  other;  they  then  affect  the  body,  which  is  subjected  to  con- 
siderable displacement.  The  oscillations  of  the  head  increase  in 
frequency  and  amplitude  as  the  dog  approaches  the  object,  so  at 
the  moment  of  reaching  it  he  is  thrown  far  from  it. 

In  drinking  the  same  thing  happens;  the  head  goes  further 
than  the  objective  point  and  the  muzzle  instead  of  touching  the 
surface  of  the  liquid  is  plunged  suddenly  and  deeply  into  it.  The 
head  is  then  suddenly  thrown  backwards,  and  this  movement  is 
followed  by  a  movement  of  retreat  of  the  whole  body,  which 
oscillates  for  some  time  in  an  antero-posterior  direction. 

These  disorders  of  motion  are  augmented  in  progression  on 
an  inclined  plane.  If  the  dog  attempts  to  mount  a  stairway,  the 
head  and  the  trunk  are  carried  backwards  to  an  exaggerated  ex- 
tent, and  the  animal  falls  backward.  Similar  defects  occur  in  an 
attempt  to  descend;  the  moment  the  fore  paw  touches  the  step 
the  body  and  the  head  are  thrust  forward  and  the  animal  falls, 


EXPERIMENTATION 


6l 


or  the  posterior  half  of  the  body  is  raised  above  the  anterior  half, 
and  the  dog  turns  a  somersault.  These  disturbances  are  less 
pronounced  if  he  is  able  to  lean  the  operated  side  against  a  wall. 

These  phenomena  tend  to  disappear  with  time,  but  slowly, 
more  slowly  even  than  the  disturbances  of  progression  and  station. 

Micturition  is  not  accomplished  in  the  normal,  way.  It  takes 
place  always  in  the  squatting  position.  The  hind  paws  spread 


45 

FIGS.  43  to  45.  Attitude  at  different  periods  of  reeducation  of  a  dog 
which  has  had  the  right  labyrinthine  root  and  the  right  cerebellar  hemi- 
sphere sectioned.  They  are  the  same  as  in  a  dog  which  has  simply  been 
deprived  of  the  right  cerebellar  hemisphere  but  in  the  latter  case  the 
reeducation  is  more  rapid. 

further  apart,  but  they  always  keep  in  contact  with  the  ground. 
Attempts  at  micturition  and  defecation  are  accompanied  by  severe 
antero-posterior  oscillations.  At  first  a  fall  is  inevitable. 

Coitus  is  impossible,  not  because  the  genital  instinct  is  abol- 


62  THE    FUNCTIONS    OF    THE    CEREBELLUM 

ished  or  diminished,  but  because  the  unstable  equilibrium  prevents 
it.  Luciani  even  questions  whether  there  is  not  an  exaltation  of 
the  sexual  sense.  There  is  neither  impotence  nor  sterility. 

Swimming  alone  is  still  possible,  on  condition  that  it  be  not 
too  prolonged,  since  fatigue  rapidly  supervenes.  The  healthy  side 
is  always  immersed  deeper  than  the  operated  side,  the  head  is 
slightly  inclined  towards  the  healthy  side,  and  progression  is  not 
made  in  a  straight  line  but  inclined  a  little  towards  the  healthy 
side,  so  that  the  animal  tends  to  move  in  a  circle.  When  the  dog 
comes  out  of  the  water  and  shakes  himself,  severe  oscillations 
and  displacements  of  the  body  are  produced  in  a  transverse  sense ; 
the  same  thing  happens  when  the  dog  tries  to  scratch  himself. 
Young  dogs,  which  have  never  swum  before  having  been  operated 
on,  are  able  to  swim  after  the  operation. 

Several  weeks  after  the  operation  nothing  remains  except  a 
certain  stiffness  of  the  trunk,  the  brusque  and  exaggerated  lifting 
of  the  limbs  of  the  operated  side,  some  oscillations  at  the  arrest 
of  movements,  or  in  the  change  of  attitudes,  and  the  more  prompt 
appearance  of  fatigue.  In  general,  the  movements  do  not  appear 
to  be  so  automatic  and  so  spontaneous  as  before  the  operation. 
There  is  in  them  something  intended,  something  willed.  The 
tendon  reflexes  are  exaggerated  on  the  injured  side. 

There  still  exist,  however,  disturbances  of  equilibrium  which 
can  be  easily  demonstrated.  It  suffices  to  fix  the  attention  of  the 
animal  and  to  present  to  him,  for  example,  a  piece  of  meat  a 
little  above  the  level  of  his  head ;  as  soon  as  he  lifts  his  fore  paws 
to  raise  himself  on  his  hind  quarters,  the  trunk  oscillates  mark- 
edly and  titubation  reappears  in  a  very  intense  form.  On  the 
other  hand,  the  suppression  of  sight  control  does  not  increase  the 
disturbances  of  motility.  Walking  on  an  inclined  plane  still  re- 
mains difficult. 

During  the  first  days  which  follow  the  operation,  the  dog  does 
not  bark;  he  recommences  to  bark  only  after  he  can  stand  up. 
Fatigue  supervenes  more  rapidly  than  in  a  normal  dog.  His  first 
attempts  to  walk  exhaust  him  very  soon ;  respiration  becomes 
more  rapid  almost  immediately,  and  before  making  a  new  attempt 
he  rests  for  some  time. 

Russell  has  noted  anesthesia  and  analgesia  of  the  side  of  the 
operation  during  the  first  days  which  follow  the  operation. 


EXPERIMENTATION  63 

II.   Destruction  of  the  Two  Lateral  Lobes 

When  the  two  lateral  lobes  are  removed  (Russell),  the  initial 
phenomena  are  the  following :  The  two  eyes  look  downward  and 
outward,  nystagmic  shocks  direct  the  eyes  outward  and  upward ; 
they  last  only  three  days.  The  dog  is  incapable  of  standing. 
According  to  Russell,  a  motor  paralysis  affects  all  four  limbs,  the 
posterior  more  than  the  anterior.  Instability  is  manifested  and 
exaggerated  under  the  influence  of  excitations  or  attempts  at 
voluntary  movement,  but  the  rotatory  movements  are  lacking. 
The  anterior  extremities  are  rigid,  stretched  at  a  right  angle  to 
the  trunk,  the  posterior  extremities  are  less  so;  the  tendon  re- 
flexes are  exaggerated.  There  is  neither  deviation  of  the  head 
nor  deviation  of  the  eyes.  Anesthesia  and  analgesia  of  the  limbs 
are  transitory. 

III.    Total  Destruction  of  the  Cerebellum 
(Fig.  46) 

The  initial  phenomena  are  less  striking  in  intensity  than  those 
seen  after  destruction  of  one  hemisphere.  Reeducation,  how- 
ever, is  slower  and  less  complete. 

Total  destruction  of  the  cerebellum  is  not  easy  to  effect;  either 
one  takes  away  too  much,  or  one  does  not  take  away  enough ;  in 
other  words,  it  is  difficult  to  remove  the  whole  cerebellum  and  to 
remove  nothing  but  the  cerebellum.  This  is  why  after  autopsy 
it  is  necessary  to  make  a  microscopical  examination  of  a  series 
of  sections  of  the  medulla  and  the  rhombencephalon  to  be  certain 
that  contiguous  structures  have  been  respected. 

Immediate  Phenomena. — Decubitus  occurs  indifferently  upon 
one  side  or  the  other.  The  head  is  in  forced  extension,  bent  back- 
wards without  lateral  inclination,  the  trunk  describes  a  similar 
incurvation  (opisthotonos),  the  limbs  are  contracted  in  extension, 
particularly  the  anterior  ones.  Movements  of  rotation  around 
the  longitudinal  axis  are  less  frequent  and  less  rapid  than  after 
destruction  of  one  hemisphere,  and  persist  for  a  shorter  time. 
They  are  more  manifest  when  the  destruction  has  not  been  com- 
plete or  perfectly  symmetrical.  Rotation  then  Occurs  towards 
the  side  most  injured.  The  menagery  movements  are  sponta- 


64 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


neous,  and  are  more  often  produced  by  peripheral  or  sensory 
stimuli,  more  particularly  by  auditory  sensations.  According  to 
Munk  such  movements  would  be  absent  were  the  destruction  total 
and  symmetrical.  When  the  destruction  is  complete  and  Sym- 
metrical, the  rotatory  movements  are  replaced  by  a  hypertension 
of  the  head  and  of  the  trunk,  with  a  tendency  to  draw  back,  and 
accompanied  by  retropulsion.  The  limbs  are  in  a  state  of  hyper- 
extension. 


FIG.  46.    Total  destruction  of  the  cerebellum  in  a  dog.    Only  a  small 
fragment  of  the  right  hemisphere  remains. 

The  eyeballs  generally  show  horizontal  nystagmus.  Strabis- 
mus is  the  consequence  of  an  incomplete  and  asymmetrical  de- 
struction, the  eyes  being  deviated  to  the  side  of  the  cerebellar 
hemisphere  the  most  affected.  During  the  first  two  or  three 
days  which  follow  the  operation,  there  are  troubles  of  deglutition 
and  vomiting,  which  are  the  consequence  of  compression  of  the 
organs  in  the  neighborhood.  The  same  phenomena  may  be  ob- 
served after  a  unilateral  destruction  of  the  cerebellum.  Glyco- 
suria  has  also  been  noted  (Luciani). 

Phase  of  Restoration.  Later  Phenomena. — After  some  days 
the  dog  makes  efforts  to  lie  upon  the  abdomen  (Fig.  47).  He 


EXPERIMENTATION  65 

hardly  succeeds  at  all  until  after  there  has  been  considerable 
lessening  of  the  contractions  of  the  limbs,  of  the  head,  and  of  the 
trunk.  Then  he  is  able  to  pass  from  the  side  to  the  abdominal 
position.  The  first  attempts  generally  cause  an  increase  in  or  a 
reappearance  of  the  contractions.  The  animal  then  falls  imme- 


FIG.  47- 


Attitude  of  a  dog  subjected  to  a  total  destruction  of  the 
cerebellum.     Extreme  abduction  of  front  legs. 


diately  to  the  right  or  left  side.  Little  by  little,  he  is  able  to  lie 
upon  the  abdomen  for  some  seconds.  The  fore  limbs  are  in  a 
state  of  extreme  symmetrical  abduction  (Fig.  48),  the  head  and 
the  trunk  are  the  seat  of  antero-posterior  or  lateral  oscillations; 


Gi 


FIG.  48.  Attitude  of  the  dog  during  the  first  attempt  to  walk  after 
total  destruction  of  the  cerebellum.  Abduction  of  front  legs.  (After  an 
instantaneous  photograph.) 

later  the  abduction  of  the  fore  limbs  diminishes  and  the  trunk 
is  slightly  elevated  from  the  ground,  but  the  instability  persists 
and  brings  about  a  fall  to  one  or  the  other  side.  The  instability 
is  proportionately  greater  as  the  animal  makes  efforts  to  move 
6 


66 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


himself.     When  he  is  offered  food  a  certain  distance  away  from 
him,  he  tumbles  over  himself  in  his  efforts  to  reach  it. 

After  some  days  the  hind  part  of  the  body  is  lifted  from  the 
ground,  and  the  animal  makes  strenuous  efforts  to  stand  upon  his 
four  paws  (Fig.  49).  At  first,  as  soon  as  the  hind  legs  are  in 
position,  the  oscillations  reappear  or  increase  in  amplitude,  and 
numerous  falls  occur.  .  Nevertheless,  after  a  certain  time  the  dog 
is  able  to  maintain  a  standing  position  for  some  moments,  and  he 
begins  to  learn  to  walk  again  (Fig.  50).  From  the  very  first  the 
limbs,  the  anterior  more  than  the  posterior,  are  in  marked  abduc- 
tion, each  paw  is  lifted  only  after  much  hesitation,  and  leaves  the 


H.tjillft 


FIG.  49.  Attitude  during  walking  of  the  dog  at  a  period  when  the 
amelioration  is  more  advanced.  The  anterior  limbs  are  less  in  abduction 
and  the  anterior  half  of  the  body  is  raised  higher  from  the  ground.  The 
posterior  limbs  still  remain  in  contact  with  the  ground.  (After  an  in- 
stantaneous photograph.) 

ground  suddenly  and  falls  back  in  the  same  manner.  One  does 
not  observe  the  movement  of  translation  of  the  whole  body  to 
one  side  as  seen  after  a  unilateral  destruction.  On  the  other 
hand,  an  antero-lateral  or  antero-posterior  balancing  of  the  body 
is  seen,  when  the  oscillations  increase  in  amplitude  and  eventuate 
in  a  fall  when  the  paws  are  lifted  from  the  ground. 

Lifting  of  the  limbs  follows,  but  very  slowly  and  with  great 
irregularity.  Each  movement  considered  by  itself  is  -abnormal ; 
The  paws  are  raised  either  too  suddenly  or  too  high. 

When  the  fore  limbs  are  lifted  and  projected  forward,  the 


EXPERIMENTATION  67 

head  is  raised  and  carried  backward,  and  if  the  movement  has 
been  forcible  the  animal  falls  backwards.  In  the  same  way 
when  the  fore  paws  again  touch  the  ground  and  the  hind  paws 
are  raised  in  their  turn,  the  body  is  likely  to  be  thrown  forward 
and  the  muzzle  bumps  the  ground.  H.  Munk  (1907)  described 
this  gait  as  the  "jumping  gait."  The  hind  half  of  the  body  being 
lowered,  the  front  half  with  the  head  and  the  front  extremities  is 
raised  suddenly,  and  then  lowered,  then  the  posterior  half  is 
raised  with  the  posterior  limbs  in  extension,  immediately  the  two 


FIG.  50.  Walking  and  standing  at  a  period  still  more  advanced.  The 
animal  can  sustain  itself  on  its  four  paws  in  abduction.  (After  an  instan- 
taneous photograph.) 

extremities  make  a  bound  forward  in  such  a  manner  that  they 
all  touch  the  ground  at  the  same  time  or  nearly  so.  According 
to  the  same  author  these  movements  lack  proportion.  That  is 
why  the  animal  tumbles  forward  or  falls  backwards.  At  a  more 
advanced  period  of  the  reeducation  the  muzzle,  or  the  rump, 
touches  the  ground  more  or  less  suddenly.  However,  these 
movements  do  not  immediately  succeed  one  another.  Between 
the  lowering  of  the  fore  paws  and  the  elevation  of  the  hind  quar- 
ters there  is  always  a  slight  pause.  In  this  mode  of  progression 
the  head  is  immobile  as  if  the  neck  were  ankylosed  and  the  fore- 
head lowered  to  the  level  of  the  back.  According  to  Munk,  the 
movements  of  the  extremities  are  normal  during  walking.  From 


68  THE    FUNCTIONS    OF    THE    CEREBELLUM 

the  second  week,  he  says,  the  dog  lifted  by  the  skin  of  its  barck 
executes  movements  of  walking  with  its  extremities ;  in  the  same 
way  a  dog  lying  down,  which  changes  its  position,  makes  a  normal 
movement  of  walking.  According  to  Lewandowsky  the  gait  of 
dogs  deprived  of  the  cerebellum  would  be  comparable  to  that  of  a 
cock  or  a  cat.  Either  the  animal  lifts  his  paws  in  the  exaggerated 
manner  of  a  cock,  or  he  drags  them  like  a  cat. 

With  time,  however,  the  gait  becomes  less  irregular ;  the  abduc- 
tion of  the  members  diminishes;  the  movements  are  produced 
with  more  rapidity  and  the  balancing  of  the  body  is  less  violent. 
In  spite  of  this,  however,  for  weeks  and  even  for  months  waver- 
ing, tremors,  and  oscillations  of  the  body  can  be  observed.  The 
animal  does  not  regain  his  suppleness,  he  walks  as  though  anky- 
losed.  Progression  is  not  made  in  a  straight  line.  The  trunk 
is  displaced  first  on  one  side  and  then  on  the  other ;  the  limbs  are 
lifted  either  too  suddenly  or  too  high.  The  rhythm  of  walking 
or  of  running  is  altogether  upset.  Fatigue  supervenes  rapidly, 
the  animal  is  obliged  to  rest  frequently.  According  to  Munk, 
there  is  no  further  progress  after  eight  or  ten  weeks. 

The  disturbances  observed  during  feeding  are  comparable  to 
those  which  have  been  noted  in  the  case  of  unilateral  destruction 
of  the  cerebellum.  There  is  a  tremor  of  the  head  which  increases 
in  amplitude  as  it  nears  the  object.  The  tremor  is  sufficiently 
violent  to  occasion  lateral  displacements  of  the  body.  Similar 
phenomena  are  produced  when  the  animal  drinks ;  when  the  head 
is  lowered  towards  the  trough  it  is  projected  suddenly  downward 
and  forward,  the  muzzle  bumps  the  bottom;  the  animal  tries  to 
lift  it  out  and  then  this  movement  is  also  too  sudden ;  the  head  is 
thrown  backwards  and  carries  the  body  with  it,  and  the  animal 
draws  back. 

The  troubles  of  equilibrium  and  motility  are  at  their  maximum 
during  progress  on  an  inclined  plane,  such  as  the  ascent  or  descent 
of  a  flight  of  stairs.  This  is  accompanied  by  falls  and  somer- 
saults. During  the  ascent  of  the  stairway,  as  soon  as  the  fore 
paw  is  lifted  to  be  put  upon  a  step,  the  head  is  placed  in  hyperex- 
tension  as  well  as  the  body  and  the  animal  falls  backward;  in- 
versely, during  a  descent  as  soon  as  a  fore  paw  is  put  down  a 
step,  the  body  frequently  slides  forward  and  the  animal  rolls  over, 
or  it  may  fall  to  one  side.  These  disturbances  are  almost  exactly 


EXPERIMENTATION  69 

the  same  as  those  noted  in  the  case  of  destruction  of  the  lateral 
lobe,  but  they  are  more  intense  and  more  persistent.  With  prac- 
tice these  disturbances  are  progressively  attenuated,  so  that  after 
a  certain  time  the  mounting  of  a  stairway  only  causes  some 
hesitation  and  some  oscillations.  It  is  however,  never  so  rapid, 
and  never  so  automatic  as  it  is  in  the  case  of  a  normal  dog.  Dur- 
ing micturition,  defecation  and  coitus,  the  disturbances  are  anal- 
ogous to  those  produced  by  the  destruction  of  one  hemisphere, 
but  they  are  more  intense  and  last  longer. 

Swimming  is  much  less  disturbed  than  walking.  The  main- 
tenance of  equilibrium  in  water  is  preserved  even  when  uncer- 
ible  with  the  preservation  of  equilibrium.  Wersiloff  observed  a 
Fatigue  supervenes,  however,  more  rapidly  than  in  a  healthy 


FIG.  51.  Attitude  of  a  dog,  deprived  of  the  cerebellum,  which  became 
blind.  The  animal  retains  any  position  in  which  he  is  placed.  Somniform 
state.  Left  to  himself  he  preserves  without  change  the  attitude  shown  in 
the  figure. 

animal.  When  the  ability  to  walk  and  to  stand  have  been 
restored,  the  suppression  of  sight  control  does  not  sensibly  in- 
crease the  disturbances  of  equilibrium.  On  the  other  hand,  it 
cannot  be  denied  that  sight  has  a  certain  importance  during  the 
phase  of  restoration.  For  several  weeks  I  observed  a  dog  that 
had  become  blind  a  fortnight  after  operation,  in  consequence  of 
an  ophthalmia.  This  dog  never  learned  to  walk  again ;  nor  even 
to  raise  himself;  he  remained  immovable  lying  upon  the  side 

(Fig-  50- 

The  character  does  not  appear  to  have  suffered  any  notable 
modification.  The  dog  operated  upon  recognizes  the  person  who 
takes  care  of  him  and  who  brings  his  food.  For  several  weeks 
he  does  not  bark,  in  consequence,  perhaps,  of  the  fact  that  barking 
would  entail  modifications  of  the  attitude  of  the  head  incompat- 


/O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

ible  with  the  disturbances  of  equilibrium.  Wersiloff  observed  a 
dog  who  never  barked  after  the  operation.  He  considered  it  a 
psychic  disturbance  (?). 

Superficial  sensibilty  does  not  appear  to  be  affected  and  the 
same  seems  to  be  the  case  with  deep  sensibility.  Luciani,  how- 
ever, has  observed  a  slight  retardation  in  the  response  to  tactile 
impressions.  Ducceschi  and  Sergi  observed  a  certain  retardation 
in  the  correction  of  movements.  Lewandowsky  insists  upon  the 
fact  that  animals  deprived  of  their  cerebellum  place  their  ex- 
tremities in  altogether  abnormal  positions,  and  that  they  do  not 
rectify  the  abnormal  positions  in  which  they  may  be  placed.  For 
instance,  a  dog  that  has  been  laid  on  a  table  with  one  paw  hang- 
ing over  the  edge  of  the  table,  does  not  draw  it  back.  The  whole 
hind  quarters  may  be  suspended  outside  the  limits  of  the  table 
without  any  reaction  on  the  part  of  the  animal.  On  the  other 
hand,  when  the  animal  tries  to  seize  a  bone,  very  often  the  paw 
passes  over  it.  This  phenomenon,  as  will  be  seen  further  on, 
may  be  explained  quite  otherwise  than  by  attributing  it  to  a  dis- 
turbance of  sensibility.  Moreover,  the  delay  in  the  correction 
of  vicious  attitudes  occurs  not  only  in  the  limbs  of  the  side 
operated  on,  but  also  in  those  of  the  side  not  operated  on.  The 
correction  is  only  a  little  more  slow  on  the  operated  side.  When 
the  animal  commences  to  walk  it  is  more  difficult  to  make  the 
limbs  take  abnormal  positions.  (For  the  interpretation  of  these 
phenomena  see  Chapter  IX.) 

The  sense  of  pain  seems  to  me  to  be  intact.  Russell,  however, 
noted  the  absence  of  a  reaction  to  pain  in  the  fore  paw  of  the 
side  operated  on,  and  in  the  two  hind  paws.  Lewandowsky  also 
contends  that  the  sensibility  of  the  skin  to  pain  is  diminished  for 
an  appreciably  long  time  after  the  destruction  of  the  cerebellum. 

IV.    Total  Destruction  of  the  Vermis 
(Fig.  52) 

Immediate  Phenomena. — As  soon  as  the  animal  tries  to  raise 
himself  upon  his  paws,  the  head  is  forcibly  drawn  back,  the  trunk 
is  bent  in  the  same  direction  and  the  front  limbs  are  in  forced 
extension:  This  produces  a  fall  backwards.  In  repose  the  front 
limbs  are  no  longer  in  tonic  extension.  The  head  is  in  slight 


EXPERIMENTATION  7 1 

extension.     The  eyes  look  downward  and  vertical  nystagmic  oscil- 
lations take  place. 

Phase  of  Restoration.  Later  Phenomena. — The  following 
days,  at  rest,  the  animal  lies  upon  the  abdomen,  the  fore  paws 
are  folded  backwards  along  the  body,  the  hind  ones  directed 
forward  and  very  much  separated,  the  head  is  stretched  out  in 
front  and  rests  upon  the  ground.  From  the  third  day  station  on 
the  four  paws  is  possible,  but  the  body  and  the  head  are  the  seat 
of  rather  severe  antero-posterior  and  transverse  oscillations.  The 
anterior  and  posterior  limbs  are  widely  separated,  the  posterior 


FIG.  52.    Total  destruction  of  the  vermis. 

always  directed  forward  in  an  exaggerated  fashion.  During  the 
six  or  seven  first  days  progression  is  impossible.  When  one 
offers  the  animal  a  piece  of  meat  and  he  lifts  a  paw  to  approach  it 
he  immediately  draws  back  several  steps  and  finally  falls  either 
backward  or  on  the  side  (Fig.  52). 

Five  or  six  days  after  the  operation  the  animal  is  able  to  take 
hold  of  food,  but  this  action  augments  the  disturbances  of  sta- 
tion, and  provokes  very  intense  antero-posterior  oscillations.  It 
(is  more  difficult  for  it  to  drink,  and  at  every  attempt  the  head  is 
drawn  back  brusquely  entailing  a  backward  fall. 


72  THE    FUNCTIONS    OF    THE    CEREBELLUM 

A  week  after  the  operation  the  ability  to  progress  forward 
commences.  The  fore  paws  are  spread  widely  apart  and  the 
hind  limbs  are  also  in  marked  abduction,  and  held  in  an 
exaggerated  manner  in  front  of  the  natural  position  (Fig.  53). 
They  are  detached  from  the  ground  with  difficulty,  then  suddenly 
lifted  and  replaced  in  as  sudden  a  fashion.  The  hind  quarters 
describe  a  series  of  zig-zag  movements,  being  carried  alternately 
to  the  right  and  to  the  left.  Walking  is  at  first  slow  and  ac- 
companied by  antero-posterior  oscillations  of  the  trunk.  The 
oscillations  increase  during  the  taking  of  food,  defecation  and 
micturition.  They  persist  almost  indefinitely  but  become  slighter 
during  the  performance  of  these  various  acts.  They  disappear 
at  the  end  of  three  or  four  weeks,  during  standing  on  four  paws 
and  during  walking. 


H.q 


FIG.  53.     Gait  of  a  dog  deprived  of  the  vermis.     Medium  abduction  of 
anterior  limbs.    Abduction  and  projection  of  posterior  limbs. 

After  five  or  six  weeks  there  is  considerable  amelioration  in 
the  act  of  walking.  Nevertheless,  abduction  and  forward  pro- 
jection of  the  hind  paws  persists.  At  about  the  same  time  the 
deviation  of  the  eyeballs  and  the  nystagmus  have  generally  dis- 
appeared. Swimming  is  normal  even  in  the  case  of  puppies  that 
have  never  swum  before  the  operation.  I  have  observed  tonic 
hyperextension  of  the  head  and  the  front  limbs,  and  draw- 
ing back  in  other  animals;  particularly  in  the  case  of  a  rabbit, 
which  was  not  able  to  go  forward  for  several  weeks — it  always 
went  backwards. 


EXPERIMENTATION 


73 


V.   Partial  Destruction  of  the   Vermis 

In  the  cat  I  have  been  able  by  means  of  a  galvano-cautery  to 
destroy  the  nucleus  of  the  tegmentum  on  the  left  side.  The  lesion 
(after  a  histological  examination  on  a  series  of  sections)  had 
slightly  affected  the  lateral  nucleus  at  its  internal  border. 

After  the  fourth  day  the  animal  was  able  to  walk,  but  it  was 
always  drawn  backwards  and  to  the  left.  The  head  was  often 
bent  backward  vigorously  in  opisthotonos ;  it  raised  itself  on  its 


FIG.  54.  Attitude  of  a  dog  deprived  of  the  left  cerebellar  hemisphere 
and  the  vermis.  Falls  backwards  and  to  the  right.  (After  an  instan- 
taneous photograph.) 

hind  quarters  and  fell  backwards.  At  the  beginning  the  front 
limbs  were  in  hypertension  and  spread  wide  apart.  The  follow- 
ing days  it  displaced  itself  with  bounds  as  if  animated  by  a  veri- 
table movement  of  translation  at  first  to  the  left  and  then  to  the 
right.  This  movement  was  also  combined  with  a  motion  of 
drawing  back.  The  limbs  were  in  a  condition  of  tonic  extension. 
The  head  was  rigid  and  slightly  inclined  to  the  left.  The  hind 
paws  were  lifted  either  too  high  or  too  suddenly,  and  were 


74 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


replaced  in  the  same  manner,  striking  the  ground.  Walking  on 
an  inclined  plane  increased  all  these  disturbances  and  provoked 
backward  falls.  Eight  days  after  the  operation  the  movement  of 
translation  was  still  present  and  more  marked  towards  the  right 
than  towards  the  left.  These  phenomena  persisted  until  the  death 
of  the  animal  on  the  twenty-sixth  day  after  the  operation.  The 
rigidity  of  the  limbs  and  of  the  trunk  was  never  so  marked  upon 
any  of  the  other  animals  upon  which  I  have  operated.  Perhaps 
the  method  of  operation  had  something  to  do  with  it ;  that  is,  the 
destruction  by  the  galvano-cautery. 


Uplift 

FIG.   55.     Attitude  of  the  station  of  the   same  dog.     Abduction  of   the 
anterior  limbs.     (After  an  instantaneous  photograph.) 

When  the  destruction  of  the  vermis  encroaches  upon  one  of 
the  hemispheres,  or  even  on  both  of  them,  the  symptomatology 
approaches  that  following  destruction  of  the  hemisphere  or  the 
total  destruction  of  the  cerebellum  (Figs.  54  and  55). 

The  destruction  of  the  posterior  half  of  the  vermis,  pyramid 
and  declive,  gives  rise  to  the  following  phenomena  (Russell)  : 
The  immediate  or  transitory  phenomena  are  downward  and 
slightly  outward  deviation  of  the  eyeballs,  and  vertical,  rotatory  or 
variable  nystagmus.  The  animal  walks  upon  a  very  much  en- 
larged base.  Instead  of  holding  itself  upon  its  hind  paws  it  rests 
upon  that  part  of  the  limb  which  extends  from  the  ankle  joint  to 
the  toes.  Instability  of  the  head  increases  on  all  movement, 
whether  accidental  or  voluntary.  During  walking  each  fore  paw 


EXPERIMENTATION  75 

is  raised  before  the  other  one  has  touched  the  ground.  The 
posterior  limbs  stay  in  the  positions  which  have  just  been  indi- 
cated. The  dog.  thus  'gives  an  impression  of  a  circus  horse 
standing  on  his  hind  legs.  Backward  falls  are  very  frequent. 
The  rotation  movements  are  lacking ;  the  tendon  reflexes  are  exag- 
gerated. Rigidity  of  the  members  is  slight.  Sensibility  is  only 
dulled,  and  is  completely  restored  after  a  week.  When  the  de- 
struction trenches  upon  the  anterior  half  of  the  median  lobe,  the 
tendency  to  fall  backwards  is  less  marked.  These  phenomena 
become  less  marked  little  by  little,  and  after  several  weeks  it  is 
difficult  to  find  a  clearly  defined  difference  from  the  normal  con- 
dition. The  animal  is  able  to  stand  up  on  his  hind  legs  and  take 
hold  of  meat. 

The  destruction  of  the  lateral  half  of  the  posterior  part  of  the 
median  lobe  (Russell)  is  followed  by  a  slight  incoordination 
and  a  slight  rigidity  in  the  limbs  of  the  same  side,  with  an  exag- 
geration of  the  tendon  reflexes.  The  eye  on  the  side  of  the  lesion 
is  deviated  downwards  and  outwards.  There  is  nystagmus  on 
looking  towards  the  opposite  side,  and  on  looking  upwards. 

Similar  results  had  been  obtained  by  Ferrier.  He  had  noted 
that  after  lesions  of  the  posterior  part  of  the  median  lobe  the  head 
was  drawn  backward  and  the  animal  tended  to  fall  backwards 
when  he  attempted  to  walk.  Inversely  when  the  anterior  portion 
was  injured,  the  animal  stumbled  and  had  a  tendency  to  fall 
forward. 

VI.  Longitudinal  Section  of  the  Vermis 

Magendie  had  already  practiced  section  of  the  cerebellum  into 
two  .equal  lateral  halves.  Then  the  animal  appeared  to  be  alter- 
nately pushed  to  the  right  and  to  the  left  without  being  able  to 
preserve  any  fixed  position.  If  he  rolled  once  or  twice  towards 
one  side,  he  turned  back  and  rolled  the  same  number  of  turns 
towards  the  opposite  side. 

On  the  other  hand  Ferrier  had  observed  that  the  disturbances 
of  equilibrium  are  of  slight  importance,  and  that  there  is  no  trace 
of  a  tendency  to  vacillation  or  to  rotation.  When  the  lesions  are 
symmetrical,  the  disturbances  of  equilibrium  are  always  slight. 

These  are  the  results  of  the  latest  experiments  of  Tren- 
delenburg. 


76  THE    FUNCTIONS    OF    THE    CEREBELLUM 

During  the  first  days  the  spastic  phenomena  are  lacking,  as 
well  in  the  limbs  as  in  the  vertebral  column.  When  the  animal 
attempts  to  raise  itself  the  limbs  are  abducted-  and  the  trunk  is 
close  to  the  ground.  The  oscillations  of  the  body  which  appear 
when  the  animal  stands  are  exaggerated  when  it  eats  and  drinks. 
At  the  end  of  fifteen  days  all  these  symptoms  are  considerably 
diminished,  and  they  disappear  at  the  end  of  three  weeks.  The 
author  concludes  from  this  that  the  crossed  paths  of  the  cere- 
bellum, which  were  interrupted,  have  been  compensated  for  in 
this  very  short  time. 

VII.    Localised  Lesions  of  the  Cortex  of  the  Lateral  Lobes 

My  personal  experiments  show  that  the  disturbances  are  less 
marked  in  proportion  as  the  gray  nuclei  have  been  respected. 
Exclusively  cortical  lesions  give  rise  to  phenomena  of  the  same 
order  as  lesions  involving  both  the  cortex  and  the  central  gray 
nuclei,  but  they  are  generally  transitory  and  do  not  last  more 
than  ten  or  fifteen  days.  These  phenomena  may  be  lacking  if  the 
lesion  is  very  limited.  However,  I  make  certain  reservations  in 
view  of  more  recent  experiments  made  by  various  physiologists. 
In  my  animals  equilibration  did  not  appear  to  be  disturbed.  But 
perhaps  a  more  minute  analysis  of  the  motility  of  the  members 
might  have  revealed  some  slight  signs  which  escaped  me  (see 
page  294). 

DESTRUCTION  OF  THE  CEREBELLUM  IN  THE  MONKEY 

These  experiments  have  been  made  by  a  number  of  physiol- 
ogists, particularly  by  Luciani,  Ferrier  and  Turner,  Russell,  Lew- 
andowsky  and  Munk.  They  were  performed  almost  exclusively 
on  the  Macacus  monkey. 

The  phenomena  produced  by  total  or  partial  destruction  of 
the  cerebellum  are  altogether  comparable  with  those  which  have 
been  observed  in  dogs  and  other  mammals,  but  the  more  perfect 
skill  and  education  of  the  fore  limbs  of  the  monkey,  particularly 
the  faculty  of  prehension  possessed  by  the  hand,  permits  a  better 
study  of  the  motor  disturbances  engendered  by  a  total  or  partial 
suppression  of  the  cerebellum,  and  gives  a  more  general  point  of 
view  of  the  functions  of  that  organ. 

In  general,  the  immediate  phenomena  are  less  striking  and  the 
rotation  momements  less  marked. 


EXPERIMENTATION  77 

I.  Destruction  of  one  Cerebellar  Hemisphere 

Great  instability  with  frequent  falls  follows  the  unilateral 
destruction  of  a  lateral  lobe.  The  vertebral  column  is  curved 
presenting  a  concavity  towards  the  side  of  the  lesion.  According 
to  Russell,  the  cervical  column  is  turned  in  such  a  fashion  that 
the  side  of  the  face  corresponding  to  that  of  the  lesion  is  directed 
upward  (?).  According  to  Luciani,  the  rotation  of  the  cervical 
column  towards  the  uninjured  side  is  associated  with  strabis- 
mus and  nystagmus.  The  eye  of  the  side  operated  upon  is  devi- 
ated downward  and  inward,  that  of  the  opposite  side  upward  and 
outward.  The  animal  falls  very  frequently  and  has  a  tendency 
to  turn  around  the  longitudinal  axis.  The  movement  follows 
the  direction  of  torsion  of  the  head  and  neck,  or  the  strabismus, 
that  is  to  say,  from  the  side  operated  upon  towards  the  healthy 
side  (Luciani).  But  if  one  determines  the  direction  of  the 
movement  according  to  the  side  upon  which  the  animal  falls,  the 
movement  is  made  towards  the  operated  side.  In  seeking  to  fix 
the  direction  of  rotation  according  to  certain  rules  and  to  interpret 
from  these  the  results  obtained  by  the  various  authors,  one  can- 
not be  absolutely  sure  that  all  agree  that  the  rotation  takes  place 
in  the  same  direction.  Not  having  made  any  personal  observa- 
tions upon  the  monkey,  as  I  have  done  upon  the  dog,  I  am  unable 
to  give  a  definite  answer  to  this  question. 

During  the  first  days  the  monkey  lies  upon  his  stomach,  the 
members  in  abduction,  with  the  side  operated  upon  at  a  lower 
level  (Luciani).  When  he  wishes  to  displace  himself  he  climbs 
in  a  sort  of  a  manner,  the  limbs  being  very  widely  spread  apart. 
During  these  various  efforts  the  head  and  the  trunk  oscillate ;  the 
movements  of  the  hand,  especially  those  of  the  side  operated 
upon,  are  very  irregular  and  any  support  within  reach  is  grasped. 
Instead  of  being  in  extension  as  in  the  dog,  the  anterior  limbs 
are  flexed. 

From  the  first  few  days  which  follow  the  operation  the  animal 
is  able  to  climb.  The  following  days  there  is  an  amelioration  of 
this  condition;  the  animal  walks  better;  the  limbs  of  the  injured 
side  are  stiffer  and  held  further  from  the  body  than  those  of  the 
other  side;  they  are  raised  and  replaced  without  coordination. 
Later,  they  are  moved  in  a  peculiar  manner  which  Ferrier  and 
Turner  compare  to  a  movement  of  creeping.  The  animal  often 


78  THE    FUNCTIONS    OF    THE    CEREBELLUM 

describes  circular  movements  towards  the  operated  side;  the 
tremors  and  oscillations  diminish  during  repose,  and  reappear  to 
a  sufficiently  marked  degree  during  voluntary  effort.  Ferrier  and 
Turner  compare  this  tremor  with  the  intention  tremor  of  multiple 
sclerosis. 

When  the  monkey  is  seated  upon  the  ischiatic  callosities,  he 
fixes  himself  on  the  ground  with  two  hands  or  with  one  hand 
only,  or  he  may  hold  a  piece  of  furniture.  To  avoid  the  oscil- 
lations of  the  head  or  of  the  body  he  will  lean  his  head  against 
a  wall. 

These  phenomena  become  less  marked  by  degrees.  The 
corrections  are  produced  more  rapidly  in  the  monkey  than  in  the 
dog  (Luciani).  One  or  two  months  after  the  operation  the 
monkey  hardly  differs  from  a  normal  monkey  except  for  the 
slight  incurvation  of  the  vertebral  column,  and  the  incoordina- 
tion  of  the  movements  of  the  limbs  of  the  operated  side. 

The  hand  is  less  dextrous  on  the  operated  side  than  on  the 
other  side.  The  animal  uses  it  less  voluntarily  (Luciani).  The 
movements  of  prehension  are  abnormal.  When  he  uses  this  hand 
he  seizes  the  object  either  too  much  on  one  side  or  too  near  to 
him  or  too  far  from  him  (Lewandowsky).  The  movement  is 
not  properly  measured,  but  there  is  no  deviation  in  a  determinate 
sense.  In  the  same  way  he  does  not  hold  an  object  readily  in  his 
hand.  Lewandowsky  notes  besides  some  disturbances  in  the  ap- 
propriateness of  the  movements.  For  instance,  when  the  monkey 
wishes  to  climb  he  seizes  the  bar  between  the  third  and  the  fourth 
finger.  These  last  facts  are  contested  by  Munk.  According  to 
him  the  monkey  only  exceptionally  seizes  the  bars  of  his  cage  in 
an  awkward  manner.  The  tendon  reflexes  are  exaggerated  on 
the  side  of  the  lesion. 

Luciani  contends  that  there  is  paresis  of  the  limbs  of  the 
operated  side.  Russell  holds  that  the  posterior  limb  of  the 
opposite  side  is  thus  affected.  Ferrier  and  Turner  and  Munk 
da  not  admit  that  there  is  any  diminution  of  muscular  force. 

Disturbances  of  sensibility,  denied  by  Ferrier  and  Turner,  are 
noted  by  Russell,  for  whom  there  is  an  anesthesia  and  analgesia 
having  the  some  distribution  as  the  motor  paresis.  According 
to  Lewandowsky  deep  sensibility  is  also  disturbed.  A  monkey 
deprived  of  half  a  cerebellum  takes  abnormal  and  vicious  attitudes 


EXPERIMENTATION  79 

with  the  limbs  of  the  corresponding  side  and  does  not  correct 
positions  impressed  upon  them. 

II.    Total  Destruction  of  the  Cerebellum 

The  results  of  the  total  destruction  of  the  cerebellum  in  the 
monkey  recall  very  closely  those  which  have  been  observed  in 
the  dog. 

As  soon  as  he  comes  out  of  anesthesia,  he  attempts  to  seat 
himself,  but  does  not  succeed,  and  falls  on  the  side.  In  repose 
he  rests  upon  the  stomach,  with  the  posterior  limbs  doubled  under 
him.  When  he  attempts  to  sit  up  he  falls  always  on  the  stomach. 
He  is  obliged  to  be  satisfied  then  with  moving  the  head  and  the 
extremities.  In  order  to  feed  he  attempts  to  crawl ;  if  he  tries  to 
go  to  the  right,  he  rolls  to  the  right;  if  he  tries  to  go  to  the  left, 
he  rolls  to  the  left.  If  he  succeeds  in  raising  himself  to  a  sitting 
position  or  a  standing  position  he  falls  almost  immeditely,  either 
forward,  backward  or  to  the  side.  He  can  hold  himself  seated 
when  he  seizes  a  bar  of  the  cage;  he  falls  as  soon  as  he  lets  go. 

During  the  first  few  days  it  stays  lying  on  its  stomach,  with 
the  posterior  and  anterior  limbs  in  abduction,  the  knees  and  the 
shoulders  flexed ;  the  abduction  persists  during  attempts  to  walk. 
In  repose  the  tremors  disappear  fairly  rapidly,  but  reappear  upon 
the  occasion  of  the  least  effort  or  voluntary  movement.  They 
present  the  same  characters  as  the  so-called  intention  tremor  of 
multiple  sclerosis.  For  this  reason  the  animal  is  not  able  to  feed 
itself ;  from  the  first  days  it  attempts  to  climb  but  in  an  oscillating 
manner.  The  gait  is  vacillating  and  awkward.  The  animal  is 
carried  either  too  far  to  the  right  or  to  the  left,  and  the  trunk 
is  drawn  to  one  side  or  the  other.  Hence  there  are  frequent 
falls,  fatigue  supervenes  quickly,  and  the  necessity  for  repose 
ensues.  The  gait  gradually  amends,  but  it  never  becomes  com- 
pletely normal.  It  resembles  at  first  the  walk  of  a  drunken  man, 
and  later  it  becomes  slow  and  dragging.  According  to  Munk, 
progress  ceases  at  the  end  of  five  weeks.  The  animals  operated 
upon  do  not  execute  movements  as  well  as  healthy  ones,  they  stay 
wavering  and  awkward;  they  have  occasional  falls  and  move 
their  limbs  less  frequently.  They  do  not  rise  without  some 
object  to  hold  on  to.  They  can  climb. 

The  tremor  of  the  arms  becomes  slighter  but  always  persists. 


8O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

In  spite  of  this  these  monkeys  are  able  to  execute  a  great  num- 
ber of  movements,  eat  from  their  hands,  catch  flies,  etc.  (Munk). 
The  tendon  reflexes  remain  exaggerated.  The  disturbances 
of  muscular  force,  admitted  by  Luciani,  are  denied  by  Ferrier  and 
Turner,  and  Munk. 

III.    Destruction  of  the  Vermis 

The  destruction  of  the  median  lobe  entails  disorders  of  a 
character  less  grave  than  does  the  total  destruction  of  the  cere- 
bellum. After  the  awakening  the  head  has  a  certain  tendency  to 
extension,  and  when  the  animal  attempts  to  rise,  he  often  falls 
backwards  or  upon  one  side  or  the  other.  In  the  first  attempts 
to  walk  the  limbs  are  in  marked  abduction,  the  stomach  close  to 
the  ground  and  the  body  has  a  balancing  movement.  When  they 
are  not  supported  the  head  and  the  neck  have  an  almost  constant 
tremor.  These  disturbances  gradually  diminish.  The  balancing 
movement  is  less  extensive,  the  limbs  less  widely  stretched  apart, 
but  during  walking  they  are  lifted  too  high.  On  the  other  hand, 
they  do  not  tremble,  only  the  tremor  of  the  head  persists  for  a 
long  time.  During  the  first  days,  the  backward  falls  are  very 
frequent  and  occur  spontaneously.  The  same  phenomena  are 
produced  when  the  destruction  involves  only  the  posterior  portion 
of  the  vermis  (Ferrier  and  Turner),  or  when  the  vermis  has 
been  divided  in  the  median  line. 

A  monkey  in  which  Ferrier  had  destroyed  the  posterior  por- 
tion of  the  median  lobe  with  the  actual  cautery  was  able  to  stay 
seated  easily  by  holding  to  a  support;  if  it  let  go  it  tended  to  fall 
upon  the  back.  In  the  same  way  during  walking  and  running  it 
fell  or  tumbled  backward. 

DESTRUCTION  OF  THE  CEREBELLUM  IN  FISHES  AND  IN  REPTILES 

A  destruction  limited  exactly  to  the  cerebellum  is  difficult  to 
accomplish.  The  cerebellum  in  fishes  is  reduced  to  a  fold  which 
is  very  thin  and  very  narrow,  and  one  always  runs  the  risk  of 
removing  too  much.  Vulpian  and  Philippeaux  made  many  ex- 
periments on  fish,  particularly  on  the  carp  and  tench,  and  were 
not  able  to  observe  any  recognizable  modification  of  movement 
as  long  as  they  removed  the  free  portion  of  the  cerebellum  only. 
The  fish  swam  as  well  after  as  before  the  operation.  On  the 


EXPERIMENTATION  8 1 

contrary  as  soon  as  the  instruments  touched  the  cerebellar  pedun- 
cles the  movements  became  very  disordered,  "  the  fish  becomes 
very  much  agitated,  it  swims  in  turning  round  upon  itself,  and 
moves  its  fins  in  a  very  incoordinate  manner."  According  to 
Vulpian  these  symptoms  are  not  to  be  imputed  to  the  suppression, 
but  are  due  to  the  irritation  of  the  cerebellar  peduncles. 

Luys  observed  after  operation  that  the  movements  of  swim- 
ming were  slow  and  uncertain.  The  body  swayed  from  one  side 
to  the  other,  like  a  floating  body  without  direction  and  reduced 
to  a  state  of  uncertain  equilibrium. 

On  the  other  hand  Steiner  affirms  that  the  ablation  of  the 
cerebellum  in  fish  is  not  followed  by  any  disturbance  whatever. 

To  sum  up,  the  effects  of  the  destruction  of  the  cerebellum 
in  fishes,  according  to  Vulpian,  Luys  and  Steiner,  are  less  note- 
worthy than  they  are  in  birds  or  in  mammals.  The  most  of  these 
experimental  researches,  however,  were  not  completed  by  an 
anatomical  examination  which  would  permit  us  to  maintain  that 
the  lesion  had  not  affected  some  of  the  neighboring  organs. 

The  same  remarks  apply  to  the  researches  which  have  been 
made  upon  the  cerebellum  of  reptiles  and  batrachians.  We  can- 
not accept  the  results  except  with  certain  reservations,  since  they 
have  not  been  controlled  by  a  minute  anatomical  examination. 

After  the  destruction  of  the  cerebellum,  the  frog  moves  its 
legs  in  various  ways  without  coordination  so  that  according  to 
Flourens,  "  there  is  no  longer  any  real  gait."  On  the  other  hand, 
according  to  Steiner,  the  movements  are  only  less  precise.  Vul- 
pian and  Philippeaux  were  not  able  to  observe  any  great  disturb- 
ances of  locomotion. 

In  the  adder,  the  undulations  which  constitute  the  mode  of 
progression  of  this  animal,  and  which  are  so  regular  and  so 
nicely  coordinated,  become  irregular  and  incoordinated.  "  The 
animal  does  not  advance  at  all,  and  the  vain  efforts  which  exhaust 
it  do  not  enable  it  to  change  its  position.  The  lizard  is  not  able 
to  walk,  nor  to  hold  itself  up  upon  its  paws"  (Flourens). 

DESTRUCTION  OF  THE  CEREBELLUM  IN  BIRDS 

The  larger  number  of  the  experiments  of  Flourens  were 
made  upon  the  cerebellum  of  birds,  and  more  particularly  upon 
the  cerebellum  of  the  pigeon.  He  repeated  them  on  the  turkey, 

7 


82  THE    FUNCTIONS    OF    THE    CEREBELLUM 

the  magpie,  the  swallow,  the  duck,  etc.  The  cerebellar  mutila- 
tions were  followed  by  a  loss  of  harmony  of  the  movements  of 
coordination  and  equilibration.  The  symptoms  are  the  more 
marked  as  the  destruction  is  the  more  profound.  Flourens  sup- 
pressed the  cerebellum  in  the  pigeon  in  successive  layers.  Fol- 
lowing the  ablation  of  the  first  layers  there  was  nothing  further 
produced  than  weakness  and  disharmony  of  movement.  During 
the  destruction  of  the  median  layers  the  animal  executed  sudden 
objectless  movements,  it  was  only  upon  the  destruction  of  the 
deeper  layers  that  the  animal  lost  the  faculty  of  jumping,  flying, 
walking  and  standing  up,  which  had  been  more  and  more  dis- 
turbed by  the  superficial  and  median  mutilations.  "  Placed  on 
the  back  the  pigeon  was  unable  to  raise  itself,  it  moved  wildly 
and  continually  but  never  in  a  firm  and  determined  manner."  It 
was  unable  to  hold  itself  in  a  standing  position  except  by  the 
aid  of  its  tail  and  wings.  When  it  walked  it  progressed  like  a 
drunken  man  going  too  far  to  one  side  or  the  other.  It  wav- 
ered and  fell  frequently. 

According  to  Flourens  these  diverse  coordinations  are  not 
lost  simultaneously.  In  proportion  as  the  animal  loses  its  cere- 
bellum it  loses  gradually  the  faculties  of  flying,  then  of  walking, 
and,  finally,  of  being  able  to  stand  upright.  One  can  at  will  sup- 
press only  flight,  or  suppress  flight  and  walking,  or  suppress  all 
at  the  same  time,  flight,  walking,  and  the  ability  to  stand  up. 
When  the  cerebellum  is  thus  destroyed  by  successive  sections, 
each  of  these  faculties  is  progressively  altered  before  being  com- 
pletely lost. 

"  The  animal  commences  by  not  being  able  to  stay  for  a  long 
time  upright  upon  its  legs,  it  staggers  almost  every  instant.  Then 
its  feet  are  not  sufficient  to  preserve  station  and  it  is  obliged 
to  have  recourse  to  its  wings  and  its  tail;  finally,  any  fixed  or 
stable  condition  becomes  impossible." 

It  is  the  same  in  the  case  of  the  gait,  which  is  from  the  very 
beginning  staggering  as  in  drunkenness.  When  the  mutilations 
are  deeper  the  animal  is  unable  to  walk  except  with  the  help 
of  its  wings,  and  finally  it  is  unable  to  walk  at  all.  Par- 
tial resections  of  the  organs  do  not  determine  any  except  tem- 
porary disturbances.  In  a  young  cock  from  which  Flourens  had 
taken  the  whole  superior  half  of  the  cerebellum,  wavering  dimin- 


EXPERIMENTATION  83 

ished  from  the  fourth  day  after  the  operation,  fifteen  days  later 
equilibrium  was  totally  reestablished.  It  was  the  same  thing  in 
the  case  of  a  pigeon  which  had  only  been  deprived  of  half  of  the 
cerebellum.  On  the  other  hand,  a  chicken  from  which  the  whole 
cerebellum  had  been  removed,  had  not  recovered  its  equilibrium 
four  months  after  the  operation. 

Longitudinal  or  transverse  sections  of  the  organ  do  not  dis- 
turb the  functions  of  coordination  and  equilibrium  except  for  a 
few  days. 

Superficial  punctures  on  one  side  of  the  cerebellum  were  fol- 
lowed by  a  rather  marked  weakness  of  the  opposite  side,  and  the 
destruction  of  a  lateral  half,  was  followed  by  a  very  marked 
weakness  of  the  opposite  side  of  the  body. 

The  destruction  of  the  cerebellum  of  other  birds  gave  analo- 
gous results.  The  coordinations  related  to  swimming  were  equally 
disturbed,  a  duck  placed  in  the  water  made  movements  of  swim- 
ming with  its  feet  but  in  an  incoherent  and  ineffectual  manner. 

These  results  have  been  controlled  by  various  authors.  The 
symptoms  differ  a  little  according  to  whether  the  destruction  is 
total  or  partial.  In  the  last  case  the  birds  describe  circular  move- 
ments towards  the  same  side  or  towards  the  side  opposed  to  the 
lesion  (Wagner).  At  the  end  of  several  days  these  phenomena 
become  considerably  less  marked,  and  one  is  hardly  able  to  ob- 
serve anything  more  than  the  tendency  of  the  limbs  to  be  put  in 
extension  and  the  torsion  of  the  head  and  neck  and  the  peculiar 
tremor  which  Wagner  compares  with  the  tremor  of  paralysis 
agitans.  This  tremor  becomes  exaggerated  if  one  takes  hold  of 
the  animal  or  if  one  feeds  it.  Besides,  all  of  the  movements 
appear  to  be  feebler  than  in  a  normal  bird  (Dalton). 

I  intentionally  insist  very  little  upon  the  disturbances  deter- 
mined by  the  destruction  of  the  cerebellum  in  the  inferior  verte- 
brates. Most  of  the  researches  in  this  direction  were  made  at 
a  time  when  the  essential  elements  of  the  experiment  were  lack- 
ing. That  is  to  say,  the  anatomical  control,  and  the  analysis  of 
the  symptoms  was  rather  rudimentary.  Besides,  in  animals 
where  the  movements  of  the  limbs  are  only  slightly  differentiated, 
it  is  more  difficult  to  study  the  nature  and  the  mechanism  of  the 
anomalies  of  motility.  It  would,  however,  be  interesting  to  take 
up  these  experiments  again  taking  into  account  all  of  these  con- 
siderations. 


CHAPTER  III 

EXPERIMENTATION    (continued) 
STIMULATION  OF  THE  CEREBELLUM 

Stimulation  of  the  cerebellum  is  far  from  giving  such  constant 
results  as  experimental  destructions  in  animals,  or  lesions  of  the 
cerebellum  in  man. 

Whereas,  certain  physiologists  indicate  precise  reactions  in 
relation  to  the  stimulation  of  this  or  that  cerebellar  part  others 
doubt  even  the  excitability  of  the  cerebellum.  Some  deny  this 
property  to  the  cortex,  but  accord  it  to  the  central  nuclei. 

Since  it  is  impossible  to  give  a  definite  solution  to  this  prob- 
lem it  seems  best  simply  to  recount  the  results  obtained  up  to 
now  by  the  different  forms  of  stimuli  (mechanical,  chemical,  and 
electrical).  This  last  is  about  the  only  one  employed  by  contem- 
porary physiologists.  Renzi  tried  to  stimulate  the  cerebellum  of 
birds  by  means  of  a  pin,  but  without  results.  The  first  serious 
attempts  of  this  description  were  made  by  Weir  Mitchell.  He 
excited  the  cerebellum  by  applying  or  injecting  caustics  (injec- 
tions of  mercury,  applications  of  perchloride  of  iron,  or  tincture 
of  cantharides,  and  refrigeration  by  an  ether  spray).  The  im- 
mediate phenomena,  incoordination,  drawing  back  and  backward 
falls  are  of  short  duration.  The  more  enduring  phenomena  are 
characterized  by  a  rather  marked  weakness  of  all  movement, 
whether  voluntary  or  involuntary. 

Nothnagel,  stimulating  the  cortex  by  a  red  hot  needle,  pro- 
voked muscular  contractions  at  first  localized  on  the  same  side  as 
the  excitation,  and  then  generalized.  The  disturbances  are 
always  more  grave  and  persistent  when  the  stimulation  affects 
the  median  third  of  the  vermis.  Similar  results  have  been  ob- 
tained by  Baginsky. 

In  all  these  experiments  the  interpretation  of  the  results  is  a 
very  delicate  matter.  A  part  of. them  are  attributable  to  irrita- 
tion of  the  organ  and  another  part  to  destruction.  In  the  phe- 
nomena observed  by  Bouillaud,  in  1827,  in  the  course  of  his  at- 
tempts to  destroy  the  cerebellum  by  actual  cautery,  the  author 

84 


EXPERIMENTATION  8g 

himself  distinguishes  disturbances  due  to  the  destruction  of  the 
organ  and  those  which  are  the  results  of  irritation.  The  first 
consist  in  faults  of  coordination,  of  gait  and  of  station.  The 
irritation  determines  leaps,  tumbles,  pirouettes,  and  an  agitation 
analogous  to  epilepsy.  For  these  methods  (cauterization,  and 
physical  or  chemical  stimulation),  Ferrier  in  1878  substituted  elec- 
tricity and  employed  it  in  a  systematic  fashion  on  many  types  of 
animals. 

Electric  stimulation  is  applied  in  the  same  way  as  in  the  ex- 
periments made  upon  the  cerebral  cortex,  but  the  cerebellum  is 
less  easy  to  reach  than  the  cerebrum.  The  excitability  of  the 
cerebellum  is  subject  to  great  variation,  and  it  is  necessary  some- 
times to  wait  for  a  certain  time  before  the  phenomena  manifest 
themselves,  and  only  upon  a  relatively  small  number  of  animals 
was  Ferrier  able  to  obtain  any  satisfactory  results.  They  de- 
serve, however,  to  be  recorded. 

Electrical  Stimulation   of  the   Cerebellum  of  Monkeys 

I.  Pyramid  of  the  Median  Lobe. — Both  eyes  turn  to  the  left 
or  the  right  in  a  horizontal  plane,  according  to  whether  the  elec- 
trodes are  applied  to  the  left  or  to  the  right.     At  the  same  time 
forward  or  backward  movements  of  the  head  are  produced. 

II.  Superior    Vermiform    Process    (Posterior   Extremity}. — 
Both   eyes   look   directly   downwards   when   the   electrodes   are 
applied  exactly  in  the  middle  of  the  prominence.     This  looking 
down  of  the  eyes  is  generally  associated  with  a  forward  or  down- 
ward movement  of  the  head.     On  the  left  side  both  eyes  look 
down  and  to  the  left,  on  the  right  side  both  eyes  look  down  and 
to  the  left,  on  the  right  side  both  eyes  look  down  and  to  the  right. 

III.  Superior  Vermiform  Process  (Anterior  Extremity}. — In 
the  median  line,  both  eyes  look  directly  upwards.     At  the  same 
time  the  head  is  drawn  backwards.     One  notes  also  a  tendency 
to  separation  of  the  legs  and  some  spasmodic  movements  of  the 
arms.     These  movements  of  the  head  and  limbs,  according  to 
Ferrier,  are  not  due  to.  the  transmission  of  the  current  to  the 
corpora    quadrigemina.     In    all    his    experiments,    barking    and 
whining,  which  are  indices  of  an  irritation  of  the  posterior  cor- 
pora quadrigemina,  are  lacking.     When  the  stimulation  is  car- 
ried to  the  left,  the  eyes  look  diagonally  upwards  and  to  the  left. 


86  THE    FUNCTIONS    OF    THE    CEREBELLUM 

There  is  a  movement  of  the  head  upward,  backward  and  to  the 
left.  With  the  stimulation  to  the  right,  the  eyes  look  diagonally 
upwards  and  to  the  right,  and  there  is  a  movement  of  the  head, 
upward,  backward  and  to  the  right. 

IV.  Lateral  Lobe  (Semilunar  Lobule}. — On  the  left  side  the 
eyes  look  upward  and  turn  to  the  left,  on  the  right  side,  the  eyes 
look  upward  and  turn  to  the  right. 

V.  Flocculus. — The  eyes  turn  around  their  antero-posterior 
axes. 

Whatever  the  region  stimulated,  the  movements  of  the  limbs 
are  always  produced  on  the  side  stimulated.  They  are  sudden, 
spasmodic,  and  difficult  to  describe.  The  pupils  contract — more 
so  on  the  excited  side.  Nystagmus  is  often  produced  at  the  be- 
ginning of  the  stimulation. 

Electric  Stimulation  of  the  Cerebellum  in  Dogs  and  Cats 

Electric  stimulation  of  the  cerebellum  of  the  cat  and  dog  is 
difficult  and  the  field  of  experiment  is  limited.  The  proximity 
of  large  venous  sinuses  only  allows  a  very  incomplete  view  of 
the  organ. 

Pyramid. — To  the  left,  the  eyes  look  to  the  left.  To  the  right, 
the  eyes  look  to  the  right. 

Posterior  Extremity  of  the  Superior  Vermiform  Process  or 
Declive. — In  the  middle,  the  eyes  look  downward;  to  the  left, 
the  eyes  look  downward  and  to  the  left;  on  the  right,  the  eyes 
look  downward  and  to  the  right. 

Lateral  Lobe  (Right  Postero-Supcrior  Lobule}. — Both  eyes 
look  upward  and  to  the  right.  Both  eyes  look  upward  and  to  the 
left.  In  the  dog  there  is  at  the  same  time  a  rotation  around 
their  axes. 

Right  Flocculus. — Rotation  of  the  ocular  globes  around  their 
antero-posterior  axes,  first  to  the  right  and  then  to  the  left.  Con- 
traction of  the  pupils  has  been  observed.  Nothing  can  be  affirmed 
as  to  the  movements  of  the  head  or  of  the  limbs. 

Electrical  Stimulation  of  the  Cerebellum  of  Rabbits 

Median  Lobe. — In  the  superior  part  the  two  eyes  look  to  the 
right,  on  a  horizontal  plane.  Median  and  inferior  part,  the  two 
eyes  look  to  the  left  on  a  horizontal  plane. 


EXPERIMENTATION  8/ 

Lateral  Lobe,  Left  Side. — Superior  lobule,  rotation  upward 
and  inward  of  the  left  eye;  rotation  downward  and  outward  of 
the  right  eye.  Median  lobule,  rotation  upward  and  outward  of 
the  left  eye;  rotation  downward  and  inward  of  the  right  eye. 
Inferior  lobule.  The  two  eyes  turn  to  the  right  on  their  antero- 
posterior  axes. 

In  general,  there  is  produced  simultaneously  a  bulging  out- 
ward of  the  eyeballs,  movement  of  the  limbs  of  the  same  side, 
dilatation  of  the  nostrils,  and  movements  of  the  ears. 

Electrical  Stimulation  of  the  Cerebellum  of  Pigeons 

There  is  produced  no  movement  of  the  eyes.  The  head  is 
drawn  backwards  and  to  the  stimulated  side.  The  homolateral 
wing  flaps  and  the  corresponding  leg  is  retracted. 

Electrical  Stimulation  of  the  Cerebellum  of  Fishes 

Irritation  in  the  median  line  produces  a  bulging  of  the  eye- 
balls and  upward  incurvation  of  the  tail,  and  a  stretching  out 
of  the  fins.  Irritation  on  the  right  makes  the  right  eye  bulge, 
the  tail  is  bent  to  the  right,  and  the  fins  stretched  out.  The  same 
phenomena  are  produced  when  the  stimulation  is  reversed,  but 
the  orientation  of  the  movements  is  made  to  the  left,  and  the  left 
eye  bulges. 

Ferrier  has  compared  the  effects  of  electrical  stimulation  of 
the  cerebellum  in  animals  to  the  phenomena  observed  in  man, 
when  a  galvanic  current  is  passed  through  the  cranium  at  the 
level  of  the  cerebellar  region.  These  phenomena  consist  of  ver- 
tigo— called  galvanic  vertigo.  When  the  current  is  passed  from 
the  right  to  the  left,  the  positive  electrode  or  anode,  being  applied 
in  the  right  mastoid  fossa,  and  the  negative  electrode  or  cathode 
in  the  left  mastoid  fossa,  the  subject  experiences  an  illusion  that 
the  objects  which  it  sees  are  animated  by  a  movement  comparable 
to  that  of  a  wheel  parallel  to  the  face,  which  turns  from  right  to 
left  (Purkinje).  If  the  eyes  are  closed,  the  subject  feels  that 
he  himself  is  turning,  he  feels  himself  drawn  from  right  to  left. 
At  the  same  time,  the  head  and  the  body  lean  towards  the  anode, 
and  the  eyeballs  move  in  the  same  direction,  and  are  the  seat  of 
nystagmic  shocks. 


88  THE    FUNCTIONS    OF    THE    CEREBELLUM 

The  objective  phenomena  of  galvanic  vertigo  recall  the  move- 
ments of  the  eyes,  the  head,  and  the  limbs  of  animals  whose  cere- 
bella  were  stimulated  by  Ferrier.  Galvanic  vertigo,  however, 
is  not  a  consequence  of  the  stimulation  of  the  cerebellum.  It  is 
absent  in  animals  deprived  of  the  labyrinth,  or  simply  of  the  semi- 
circular canals,  and  in  individuals  affected  with  lesions  of  the 
internal  ear,  or  of  the  vestibular  nerve.  Many  deaf  mutes  do  not 
experience  any  sensation  of  vertigo,  and  do  not  execute  any  move- 
ments of  the  head,  body,  or  eyes,  during  the  passage  of  the  cur- 
rent. Galvanic  vertigo  is  due  to  an  irritation  of  the  vestibular 
apparatus. 

The  results  obtained  by  physiologists  who  have  followed  Fer- 
rier in  this  direction  are  less  convincing.  Employing  currents 
of  minimum  intensity,  Mendelssohn  was  not  able  to  reproduce 
the  reactions  observed  by  Ferrier.  He  was  only  able  to  produce 
by  an  irritation  of  the  cerebellum,  limited  to  the  lateral  lobe,  a 
deviation  of  the  eyes  towards  the  irritated  side,  contrary  to  that 
which  is  seen  following  an  irritation  of  the  cerebral  cortex;  the 
eyeballs  often  presented  oscillatory  movements.  Dupuy  also  ob- 
tained reactions  localized  in  the  eyes,  and  most  of  the  muscular 
groups  by  exciting  different  points  of  the  cerebellum. 

Wersiloff  compares  the  effects  of  electrical,  mechanical  and 
chemical  excitation  of  the  cerebellum  with  those  obtained  by  exci- 
tation of  the  cerebrum.  Each  half  of  the  cerebellum  is  related  to 
the  corresponding  half  of  the  trunk ;  the  vermis  acts  in  the  same 
way  towards  the  two  halves  of  the  body.  The  superior  vermis 
reacts  upon  the  inferior  limbs;  the  inferior  and  posterior  vermis 
upon  the  superior  limbs.  Its  action  is  not  limited  to  this.  The 
skin  muscles  and  the  conjugate  movements  of  the  eyes  are  also 
dependent  upon  it.  Excitation  of  the  cerebellum  produces  nys- 
tagmic  movements,  horizontal,  vertical  and  rotary,  as  well  as  the 
protrusion  or  the  retraction  of  the  eyeball,  and  winking  of  the 
eyelids. 

Pruss,  whose  experiments  were  made  upon  the  dog,  admits 
the  existence  of  motor  centers  in  the  cerebellar  cortex.  Each 
hemisphere  contains  centers  for  muscles  of  the  same  side.  Exci- 
tation of  the  vermis  in  the  median  line  produces  bilateral  shocks. 

The  results  of  his  experiments  are  as  follows:  Pyramid:  De- 
viation of  the  eye  and  the  head  to  the  same  side  and  downward, 


EXPERIMENTATION  89 

homolateral  dilatation  of  the  pupil,  elevation  of  the  shoulder, 
flexion  of  the  elbow,  and  an  extension  of  the  fingers.  Tuber  of 
the  vermis:  Homolateral  rotation  of  the  head  to  the  side  and 
downward,  exophthalmis,  mydriasis,  contraction  of  the  muscles 
of  the  back  of  the  neck,  of  the  back,  and  of  the  extensors  of  the 
homolateral  anterior  extremity.  Declive:  Contractions  of  the 
muscles  of  the  back,  particularly  of  the  lumbar  region,  and  of 
the  extensors  of  the  posterior  extremity.  Culmen:  Contraction 
of  the  extensors  of  the  posterior  extremity.  Anterior  segment  of 
the  monticulus:  Movement  of  the  tail.  Uvula:  A  motor  influence 
on  the  anterior  extremity,  the  ear,  and  the  extensor  muscles 
of  the  back.  Inferior  semilunar  lobe:  The  eyes  look  downward, 
and  there  is  an  occlusion  of  the  eye  and  movements  of  the 
shoulders.  Superior  semilunar  lobe:  Contractions  in  the  exten- 
sors of  the  fore  paw.  Quadrilateral  lobe:  Contractions  of  the 
muscles  of  the  hind  paw. 

The  cortex  is  not  excitable  except  by  currents  passing  per- 
pendicular or  longitudinal  to  it.  The  longitudinal  currents  pro- 
duce tonic  contractions.  The  perpendicular  currents  produce 
clonic  contractions.  Negro  and  Roasenda  employed  bipolar  and 
unipolar  faradic  currents.  In  the  rabbit  bipolar  excitation  of  the 
crus  primum  produced  muscular  contractions  of  the  face,  and  of 
the  fore  paw  of  the  same  side,  when  the  intensity  of  the  current 
did  not  exceed  the  limit  of  excitability  of  the  region  being  ex- 
plored. With  stronger  stimulation  the  muscles  of  the  opposite 
side  contracted  at  the  same  time. 

With  unipolar  currents  they  were  able  to  localize  more  pre- 
cisely. The  centers  of  the  face  and  the  fore  paw  are  situated 
in  the  antero-lateral  lobe,  within  and  towards  the  anterior  lobe 
and  the  lobule  simplex.  The  center  for  the  face  is  situated  in 
front  of  that  of  the  fore  paw.  It  was  sometimes  necessary  to 
prolong  the  current  or  to  repeat  the  excitations  in  order  to  obtain 
a  contraction.  The  same  authors  have  made  experiments  which 
would  tend  to  show  that  in  order  to  arrive  at  the  spinal  cord  and 
the  muscles,  the  faradic  excitations  of  the  cerebellar  motor  centers 
are  not  obliged  to  traverse  the  cortical  motor  zone,  either  of  one 
side  or  the  other,  nor  the  subcortical  cerebral  motor  zone.  These 
centers  have  an  individuality  of  their  own  independent  of  the 
Rolandic  area.  The  centrifugal  motor  influx  would  appear  to  go 
through  the  middle  cerebellar  peduncles. 


gO  THE    FUNCTIONS    OF    THE    CEREBELLUM 

According  to  the  results  of  the  experiments  of  Lourie,  made 
upon  the  dog  and  the  cat,  one  is  not  able  to  show  the  existence  of 
limited  or  special  centers.  When  the  excitation  is  limited  to  a 
very  small  ajea  of  the  cerebellum,  contractions  are  produced  in 
almost  all  of  the  muscles  of  the  same  side  of  the  body.  Excita- 
tion of  the  semilunar  gyrus  produced  adduction  and  elevation  of 
the  shoulder,  concavity  of  the  vertebral  column  towards  the  oppo- 
site side,  an  inclination  of  the  anterior  limb  towards  the  right 
side  if  the  excitation  is  on  the  left,  and  inversely.  The  posterior 
limb  is  thrust  forward,  and  there  are  also  movements  of  the  tail, 
which  is  displaced  towards  the  opposite  side.  With  a  more  pro- 
longed current  and  the  excitation  on  the  left,  the  right  anterior 
limb  is  placed  in  extension,  and  turned  to  the  right,  the  left  ante- 
rior limb  is  placed  in  adduction  and  raised.  Excitation  of  the 
vermis  is  followed  by  an  extension  of  the  anterior  limb  and  an 
inclination  towards  the  excited  side.  The  vertebral  column  is 
curved  and  the  concavity  is  turned  in  the  same  direction.  Lourie 
was  not  able  to  verify  the  conclusions  of  Ferrier  as  to  the  move- 
ments of  the  eyes. 

These  contradictory  results  are  probably  explicable  by  the 
enormous  intensity  of  the  currents  employed  by  these  various 
physiologists.  Under  these  conditions  the  phenomena  observed 
are  not  in  reality  due  to  the  excitation  of  the  cerebellar  cortex, 
but  to  the  irritation  of  the  subjacent  nuclei,  and  diffusion  through 
neighboring  tracts. 

This  is  the  opinion  held  by  Horsley.  For  him  the  cerebellar 
cortex  is  not  excitable,  and,  consequently,  cannot  be  considered 
as  a  motor  center.  When  in  the  course  of  experiments  with  elec- 
tric currents,  the  electrode  is  made  to  penetrate  more  and  more 
deeply  into  the  white  substance,  that  is,  when  it  approaches  the 
central  gray  nuclei,  and  the  para-cerebellar  nuclei,  Deiters'  and 
Bechterew's,  for  example,  the  excitation  becomes  greater  and 
greater  with  a  current  less  and  less  strong.  These  nuclei  are  the 
true  efferent,  or  motor,  centers  of  the  cerebellum.  The  cortex 
being  considered  by  Horsley  as  a  receptive  center,  analogous  to 
the  visual  center  of  the  cerebral  cortex.  Movements  of  the  eyes, 
of  the  head,  the  trunk  and  the  limbs  are  represented  in  these 
nuclei.  The  contraction  produced  by  their  excitation  is  tonic  or 
hypertonic.  Oscillations  of  the  eyeballs  are  also  produced,  the 


EXPERIMENTATION  9! 

contractile  force  augmenting  with  the  excitation,  but  without 
clonicity  when  the  excitation  ceases.  The  application  of  the  exci- 
tation unilaterally  is  followed  by  a  homolateral  effect,  contrary  to 
that  which  takes  place  in  the  case  of  the  cerebrum. 

The  excitation  of  the  superior  part  of  the  dentate  nucleus 
deviates  the  eyes  and  the  head  to  the  same  side.  That  of  the 
dorsal  regions  of  the  dentate  nucleus  produces  a  bicipital  flexion 
of  the  homolateral  elbow.  Whereas,  the  excitation  of  the  basal 
region  of  the  dentate  nucleus,  with  a  maximum  stimulus,  pro- 
duces (in  addition  to  the  lateral  deviation  of  the  head  and  the 
eyes),  a  homolateral  flexion  of  the  elbow,  a  deeper  excitation  of 
the  para-cerebellar  nuclear  region  produces  a  contra-lateral  ex- 
tension of  the  elbow,  a  hyperextension  of  the  neck  and  trunk  and 
a  forcible  extension  of  the  inferior  limbs.  So  that,  while  the 
anterior  limb  is  flexed  at  the  elbow,  the  posterior  is  extended 
along  the  body. 

The  study  of  the  excitation  of  the  cerebellum  by  chemical  irri- 
tants has  been  resumed  by  Pagano.  This  author  injects  curare 
into  the  various  regions  (one  to  three  tenths  of  a  cubic  centi- 
meter of  a  one  per  cent,  solution).  There  seem  to  be  distinct 
regions  where  the  excitation  produces  isolated  movements,  either 
of  the  anterior  limb  or  of  the  posterior.  The  stimulation  of  a 
certain  point  in  the  lateral  lobe  in  the  neighborhood  of  the  vermis 
provokes  a  movement  of  retraction  and  adduction  of  the  anterior 
limb  of  the  same  side,  sometimes  a  flexion  and  adduction,  more 
rarely  of  extension.  This  movement  is  maintained.  The  atti- 
tude which  is  determined  by  it  may  last  for  several  minutes,  and 
be  reproduced  during  several  hours.  The  extirpation  of  the  re- 
spective cerebral  center  does  not  prevent  its  being  produced.  The 
excitation  of  another  point  very  near  the  first  produces  tonic 
flexion,  sometimes  extension,  of  the  posterior  limb.  The  results 
are  less  constant  for  the  anterior  limb.  In  all  these  experiments 
the  excitation  is  transmitted,  sometimes,  to  the  opposite  side. 

The  excitation  of  a  third  point  in  the  anterior  and  superior 
region  of  the  vermis,  provokes  a  tendency  to  fall  backwards, 
which  resembles  a  motor  impulse.  The  excitation  of  the  poste- 
rior part  of  the  vermis  provokes,  on  the  contrary,  a  tendency  to 
fall  forwards,  with  the  head  striking  the  ground. 

The  excitation  of  the  anterior  extremity  of  the  vermis,  mon- 


92 

ticulus,  central  lobe,  and  lingula,  gives  rise  to  a  psychic  agitation. 
Howlings,  barkings,  anxiety,  terror  and  relaxation  of  the  sphinc- 
ters, all  of  which  are  accented  under  the  influence  of  peripheral 
excitation,  particularly  auditory  ones ;  the  whole  of  which  con- 
stitutes for  Pagano  a  sort  of  psychic  strychninism.  At  its  maxi- 
mum intensity  it  ends  in  generalized  epileptiform  convulsions. 
This  is  not  due  to  a  diffusion  of  the  stimulation  to  the  neighbor- 
ing organs.  The  stimulation  of  the  quadrigeminal  bodies  engen- 
ders phenomena  which  we  must  interpret  as  an  expression  of 
sentiments,  or  of  emotions  (Ferrier). 

In  order  to  be  followed  by  results  the  injection  must  be  made 
below  the  surface.  A  sub-dural  injection  is  either  without  effect 
or  gives  different  results.  It  is  unfortunate  that  Pagano  did  not 
complete  his  experiments  by  a  series  of  sections  which  would 
have  permitted  a  topography  of  the  lesions ;  lacking  this  we  can- 
not accept  these  results  except  with  a  certain  reserve. 

By  polar  faradic  excitation  of  the  quadrilateral  lobe  (lateral 
part  of  the  lobule  simplex  of  Bolk),  in  the  dog,  Rothmann,  1910, 
obtained  movements  of  the  toes  of  the  anterior  extremity  of  the 
same  side,  movements  of  flexion  by  exciting  the  inferior  part,  and 
movements  of  extension  by  exciting  the  superior  part.  With 
stronger  currents,  the  limbs  were  elevated.  The  excitation  of  the 
anterior  lobe  provoked  movements  of  spreading  apart  and  draw- 
ing back  of  the  two  anterior  limbs. 

Excitations  of  the  cerebellum  do  not  seem  to  always  have  the 
effect  of  augmenting  the  tonus  of  certain  muscular  groups.  They 
may  have  the  reverse  effect.  According  to  Sherrington,  faradi- 
zation of  the  anterior  surface  of  the  cerebellum  produces  a  relaxa- 
tion of  the  muscles  of  the  neck,  head  and  inferior  limbs,  princi- 
pally on  the  side  excited,  in  animals  previously  in  a  state  of 
contraction  due  to  decerebration. 


CHAPTER  IV 

EXPERIMENTATION    (continued) 
EFFECTS  OF  SECTION  OF  THE  CEREBELLAR  TRACTS 

Section  of  the  Spino-cerebellar  Tracts  (Direct  Cerebellar 
Tract  of  Flechsig  and  Tract -of  Cowers}. — The  effects  of  the  sec- 
tion of  the  spino-cerebellar  tracts  (direct  cerebellar  tract  of 
Flechsig  and  tract  of  Cowers)  have  been  minutely  studied  by 
Russell,  by  Marburg,  and  lastly,  by  Bing,  in  a  work  devoted 
specially  to  this  subject.  The  results  obtained  by  Bing  are  as 
follows : 

Unilateral  Section. — In  the  upright  station  the  limbs  of  the 
operated  side  are  in  abduction.  The  posterior  limb  more  than 
the  anterior.  If  the  limbs  are  placed  in  their  normal  position  the 
animal  is  unable  to  hold  himself  upright,  and  he  immediately 
replaces  them  in  the  former  position.  The  two  extremities  are 
in  extension.  The  animal  places  very  little  weight  upon  the  limbs 
of  the  operated  side,  resting  almost  entirely  on  those  of  the  other 
side. 

Neither  oscillation  nor  wavering  is  observed,  the  trunk  is 
slightly  turned  towards  the  operated  side,  but  without  scoliosis. 
If  the  paws  of  the  operated  side  are  placed  on  their  dorsal  surface 
the  animal  nearly  always  corrects  this  vicious  attitude,  but  more 
slowly  than  a  healthy  animal  does.  There  is  nothing  abnormal 
in  the  positions  of  sitting  or  lying  down. 

During  walking  the  abduction  of  the  limbs  is  still  more 
marked.  From  time  to  time  a  stronger  movement  of  adduction 
is  produced  which  has  for  consequence  a  crossing  of  the  paw  over 
the  limb  of  the  healthy  side.  Before  lifting  the  posterior  limb 
from  the  ground  there  is  a  period  of  hesitation,  and  then  it  is 
carried  further  forward  than  that  of  the  healthy  side.  Replac- 
ing it  upon  the  ground,  the  action  is  brusque  and  sudden. 

The  gait  is  slow  and  cautious,  like  a  normal  animal  which  is 
forced  to  walk  upon  a  narrow  plank,  but  the  general  direction  is 

93 


94  THE    FUNCTIONS    OF    THE    CEREBELLUM 

well  preserved  and  there  is  no  lateral  deviation.  When  the 
animal  directs  himself  forward  he  has  a  tendency  to  describe  a 
circular  movement  towards  the  healthy  side.  If  he  is  compelled 
to  go  back,  he  turns  to  that  side.  He  is  more  awkward  when  he 
is  obliged  to  displace  himself  towards  the  injured  side  as  when  a 
piece  of  meat  is  offered  to  him  on  this  side. 

These  disorders  of  locomotion  described  under  the  name  of. 
hemiataxia  by  Bing  are  exaggerated  in  various  circumstances, 
such  as  the  occlusion  of  the  eyes,  the  acceleration  of  the  gait,  and 
the  descent  or  ascent  of  a  stairway.  i 

The  muscles  of  the  pelvis  and  of  the  thighs  are  in  no  way 
paralyzed.  There  is  a  hypotonus  of  the  operated  side,  particu- 
larly of  the  posterior  limbs.  When  the  body  of  the  animal  is  sus- 
pended vertically,  the  limbs  of  the  injured  side  give  the  impres- 
sion of  being  weaker,  and  hanging  down  further.  Their  resist- 
ance to  passive  movements  is  feebler.  The  difference  between 
the  two  sides  is  more  striking  in  the  muscles  of  the  pelvis  and  the 
scapular  girdle;  it  is  hardly  appreciable  in  the  carpal  and  tarsal 
muscles.  The  reflexes  are  normal. 

Improvement  is  rapid.  At  the  end  of  four  days  the  abduc- 
tion of  the  limbs  is  very  much  less,  as  well  in  walking  as  in 
standing.  Hypotonus  is  less  marked.  Four  weeks  after  the 
operation  the  difficulty  of  turning  toward  the  operated  side  is  the 
only  phenomenon  that  persists. 

The  ventral  bundle  (Gowers)  and  the  dorsal  bundle  (direct 
cerebellar)  seem  to  have  the  same  functions.  When  the  ventral 
bundle  is  spared,  the  disturbances  are  only  less  intense,  and  of 
shorter  duration. 

Bilateral  Section. — The  posterior  limbs  are  in  very  marked 
abduction.  The  pelvis  is  lowered  and  the  paws  are  directed  for- 
wards. The  attitude  of  the  anterior  limbs  is  variable.  Either 
they  are  spread  apart,  although  to  a  lesser  degree  than  the  poste- 
rior ones,  or,  they  are  held  very  close  together  so  that  the  paws 
touch  one  another.  The  head  is  lowered.  The  animal  has  an 
anxious,  uneasy  expression.  There  are  neither  transverse  nor 
longitudinal  oscillations.  They  do  not  occur  unless  the  paw  is 
lifted;  as  soon  as  it  is  replaced  upon  the  ground,  the  animal  re- 
sumes his  steadiness.  In  lying  down  the  attitude  is  normal;  in 
the  seated  position  the  hind  paws  are  directed  outward. 


EXPERIMENTATION  95 

During  walking  the  posterior  limbs  are  in  abduction.  If  the 
gait  is  accelerated,  the  posterior  paws  cross  one  another.  The 
same  thing  happens  to  the  fore  paws,  but  to  a  lesser  degree.  The 
body  is  projected  alternately  to  the  right  and  to  the  left,  as  well 
for  the  anterior  half  as  for  the  posterior  half.  The  posterior 
limbs  are  carried  very  far  forward,  and  the  anterior  limbs  are 
thrown  forward,  as  it  were,  the  paws  striking  the  ground  instead 
of  being  replaced  in  a  natural  manner. 

This  awkwardness  is  increased  during  the  occlusion  of  the 
eyes,  and  the  ascension  of  a  stairway,  and  when  the  animal  goes 
backwards.  The  ability  to  jump  is  preserved.  Tonus  is  dimin- 
ished. Improvement  occurs  rather  rapidly.  Four  weeks  after 
the  operation,  it  is  only  during  running,  and  in  gyratory  move- 
ments that  the  animal  experiences  any  difficulty.  In  the  standing 
position  a  slight  abduction  of  the  posterior  limbs  and  adduction 
of  the  anterior  persists. 

Bing  concludes  from  his  experiments  that  the  phenomena  in 
dogs  after  section  of  the  spino-cerebellar  bundles,  or  after  the 
destruction  of  their  terminations  in  the  cerebellum,  are  the  index 
of  a  double  primordial  alteration  which  has  effect  upon  the  mus- 
culature of  the  extremities.  It  is  a  special  disturbance  of  muscu- 
lar regulation  and  a  diminution  of  tonus. 

All  these  anomalies  of  station  and  locomotion  are  the  expres- 
sion of  disturbance  in  the  attitudes  and  movements  which  are 
seated  at  the  roots  of  the  limbs ;  that  is  to  say,  in  the  muscles  of 
the  pelvis  and  the  scapular  girdle. 

To  sum  up,  it  is  a  question  of  a  disturbance  of  the  main  move- 
ments of  the  extremities,  principally  the  combined  and  associated 
movements.  It  would  not  be  proper,  however,  to  speak  of  any 
disturbances  of  equilibrium,  as  neither  oscillations  nor  waver- 
ings are  produced. 

Section  of  the  Inferior  Cerebellar  Peduncle. — This  experi- 
ment, when  the  section  is  made  very  high,  is  difficult  to  accom- 
plish. It  is,  however,  absolutely  necessary  that  the  nuclei  of  the 
root  of  the  eighth  pair  be  respected. 

Magendie  noted  movements  of  rotation  after  section  of  one 
of  the  peduncles,  and  he  remarked  that  the  rotation  was  always 
made  from  the  side  where  the  peduncle  was  cut ;  sometimes  with 
such  rapidity  that  the  animal  made  more  than  sixty  revolutions 


96  THE    FUNCTIONS    OF    THE    CEREBELLUM 

in  a  minute.  He  obtained  also  similar  results  by  vertical  sections 
of  the  cerebellum,  but,  "  with  this  remarkable  circumstance,  that 
the  movement  was  all  the  more  rapid  as  the  section  approached 
nearer  the  origin  of  the  peduncles."  In  the  same  way,  after  the 
section  of  the  medulla  oblongata,  he  observed  a  circular  move- 
ment to  the  left  or  the  right,  like  that  of  a  circus  horse  according 
as  the  section  was  directed  to  the  right  or  the  left. 

The  symptoms  described  by  Ferrier  and  Turner,  and  later 
by  Russell,  in  the  monkey  are  as  follows : 

After  the  operation  the  animal  takes  the  following  attitude: 
The  neck  and  the  trunk  present  a  scoliosis,  with  the  concavity 
turned  towards  the  side  of  the  lesion,  the  head  is  scarcely  or  not 
at  all  twisted  on  the  longitudinal  axis ;  when  it  is  twisted  the 
occiput  is  turned  towards  the  side  of  the  lesion  and  the  chin 
towards  the  shoulder  of  the  healthy  side  (Ferrier  and  Turner). 
The  curvature  of  the  vertebral  column  is  increased  when  the  ani- 
mal is  excited,  or  when  an  attempt  is  made  to  make  him  stand 
upright.  When  he  lies  it  is  upon  the  side  of  the  injury  and  he 
returns  always  to  this  position  if  an  attempt  is  made  to  place  him 
in  another.  He  executes  rolling  movements  from  the  healthy 
side,  towards  the  side  operated  upon,  during  the  first  twenty- 
four  hours. 

The  motor  disturbances  consist  in  an  impossibility  to  stand 
upright  and  in  abnormal  attitudes  of  the  limbs.  When  the  left 
peduncle  has  been  divided  the  members  of  the  right  side  are  in 
extension,  and  those  of  the  left  side  more  or  less  flexed.  These 
attitudes  are  dependent  partly  upon  the  rigidity  and  partly  upon 
an  alteration  of  the  muscular  sense,  or  of  the  notion  of  position. 
Perhaps  also  to  a  certain  degree  of  motor  paresis.  Placed  flat 
upon  the  ground,  the  limbs  are  in  abduction;  in  this  position  the 
animal  is  capable  of  displacing  himself  by  crawling.  Later,  about 
a  week,  when  the  first  phenomena  are  somewhat  amended,  the 
animal  walks  and  runs  like  an  ataxic.  The  movements  are  inco- 
ordinate, especially  in  the  limbs  of  the  left  side  (the  posterior 
paw  of  the  side  operated  upon  is  the  last  to  recover).  It  falls 
often  on  the  left  side,  particularly  when  it  is  excited,  and  it  can- 
not remain  seated  except  by  spreading  the  legs  wide  apart  and 
holding  on  to  some  neighboring  object.  The  eyes  are  directed 
downward  and  to  the  side  opposite  the  one  operated  upon.  The 


EXPERIMENTATION  97 

displacement  outward  of  the  eye  of  the  healthy  side  is  more 
marked  than  the  displacement  inward  of  the  eye  of  the  side  oper- 
ated upon  (Russell). 

This  eye  regains  its  normal  position  before  the  other  one. 
After  the  disappearance  of  the  ocular  deviation,  the  animals  are 
still  incapable  of  directing  their  vision  towards  the  injured  side. 
Spontaneous  nystagmus  is  rare.  It  appears  only  when  the  animal 
does  not  feel  itself  secure.  The  reflexes  are  exaggerated  on  both 
sides,  more  on  the  injured  side  (Russell). 

During  the  first  week  sensibility  to  pain  (superficial  and  deep) 
seems  to  be  abolished  in  all  four  limbs.  Deep  sensation  seems  to 
return  first.  From  this  point  of  view,  the  anterior  paw  of  the 
healthy  side  is  the  first  to  be  cured  and  the  posterior  paw  of  the 
side  operated  upon  the  last  (Russell).  According  to  Ferrier  and 
Turner,  however,  there  are  no  disturbances  of  sensation. 

The  cerebral  hemisphere  of  the  side  opposite  the  lesion  is  less 
excitable  than  the  other.  After  an  intravenous  injection  of  ab- 
sinth there  are  no  convulsions  in  the  anterior  limb  of  the  side 
of  the  lesion.  The  other  three  limbs  contract.  Three  weeks 
after  the  section  of  the  inferior  cerebellar  peduncle  the  convul- 
sions in  the  two  anterior  limbs  have  different  characters ;  on  the 
side  of  the  lesion  the  convulsions  are  more  of  the  tonic  type,  on 
the  opposite  side  they  are  clonic  (Russell). 

After  hemisection  of  the  cerebellar  bundles  at  the  superior 
termination  of  the  spinal  cord,  intravenous  injections  of  absinth 
give  the  same  results  as  they  do  after  section  of  the  restiform 
body. 

The  animal  reeducates  itself  gradually.  At  the  end  of  three 
weeks  it  is  able  to  maintain  a  more  stable  equilibrium;  it  only 
falls  occasionally  when  it  is  excited,  or  when  it  is  bumped  into. 
In  a  Macacus  monkey,  which  lived  only  two  months,  the  equi- 
librium was  unstable  to  the  end  and  the  movements  of  the  limbs 
of  the  side  operated  upon  were  always  more  irregular  than  on 
the  other  side.  The  results  consecutive  to  section  of  the  inferior 
cerebellar  peduncle  may  thus  be  summed  up.  Disturbances  of 
equilibrium  in  standing  and  walking,  falls  and  movements  of  rota- 
tion around  the  longitudinal  axis  towards  the  side  of  the  lesion, 
incoordinate  movements  of  the  limbs  on  the  same  side,  incurvation 
of  the  vertebral  column  with  the  concavity  turned  towards  the 


98  THE    FUNCTIONS    OF    THE    CEREBELLUM 

injured  side.  In  one  word,  there  is  an  orientation  and  predomi- 
nance of  the  symptoms  towards  the  side  of  the  lesion. 

Section  of  the  Middle  Cerebellar  Peduncle. — This  experiment 
gave  very  contradictory  results  to  the  first  physiologists  who 
undertook  it.  Following  Pourfour  du  Petit,  who  was  the  first 
to  describe  it,  all  are  unanimous  in  observing  the  movements  of 
rotation  around  the  longitudinal  axis,  but  the  controversy  begins 
with  the  direction  of  the  rolling,  whereas,  for  Magendie  the  rota- 
tion is  made  from  the  injured  side;  Longet  describes  it  in  the 
inverse  sense.  Schiff  states  that  the  rotation  can  be  made  in 
both  directions;  everything  depends  on  the  level  of  the  section. 
The  reason  for  these  divergencies  will  be  more  fully  discussed 
in  the  chapter  "  Interpretation."  Ferrier  and  Turner  have  made 
experiments  which  were  followed  by  anatomical  verifications,  the 
results  of  which  are  more  convincing. 

These  authors  performed  transverse  section  of  the  median 
cerebellar  peduncle  of  the  monkey,  directly  outside  the  plane  of 
penetration  of  the  fifth  pair.  After  the  operation  (the  left  pe- 
duncle was  cut),  the  vertebral  column  was  curved  to  the  left,  and 
the  monkey  rolled  around  the  longitudinal  axis  to  the  left.  The 
occiput  was  turned  backwards  and  to  the  left,  and  the  chin  turned 
towards  the  right  shoulder.  The  limbs  of  the  right  side  were 
abducted  and  in  extension.  The  left  limbs  were  flexed  and  in 
adduction.  Decubitus  was  on  the  left  side. 

The  following  days  the  animal  lay  on  its  stomach,  the  body 
inclined  to  the  left;  to  move  the  body  was  slowly  drawn  forward. 
The  movements  of  rotation  diminished  progressively,  only  the 
falling  and  the  inclination  of  the  body  to  the  left  side  persisted. 
Ferrier  and  Turner,  however,  note  falls  and  movements  of  rota- 
tion to  the  right  side.  (This  last  phenomenon  appears  to  be  the 
exception.)  Whereas,  standing  up  and  walking  were  impossible, 
or  very  defective,  the  animal  was  still  able  to  climb. 

For  several  days  equilibrium  was  very  unstable.  The  trunk 
oscillated  in  standing  and  during  walking.  In  order  to  maintain 
the  sitting  position  the  monkey  was  obliged  to  hold  on  to  some 
neighboring  object. 

The  limbs  of  the  left  side  were  animated  by  irregular  move- 
ments and  oscillations,  but  there  was  no  fine  tremor.  (In  this 
case  the  superior  cerebellar  peduncle  of  the  left  side  had  been 
slightly  injured.) 


EXPERIMENTATION  99 

Equilibrium  was  progressively  and  slowly  reestablished.  In 
spite  of  that  a  slight  instability  and  a  tendency  to  fall  upon  the 
left  side  always  persisted.  The  tendon  reflexes  of  both  sides 
were  equal ;  there  was  a  very  slight  nystagmus. 

To  summarize:  The  rotation  around  the  axis  was  made  from 
the  healthy  towards  the  injured  side,  as  Magendie  had  already 
noted,  provided  that  one  determines  the  direction  of  the  rotation 
by  the  side  upon  which  the  animal  falls,  after  having  been  placed 
in  a  standing  position  upon  the  four  paws. 

Magendie  not  only  observed  that  all  lateral  sections  of  the 
pons  produced  a  movement  of  rotation,  but  that  this  movement 
was  arrested  by  a  section  of  the  opposite  side.  "  Cut  a  peduncle," 
said  Magendie,  "  and  immediately  the  animal  commences  to  roll, 
then  cut  the  one  of  the  opposite  side,  and  at  once  the  movements 
cease,  and  the  animal  loses  the  power  to  stand  up  and  to  walk." 

Section  of  the  Superior  Cerebellar  Peduncle. — This  section 
has  also  been  performed  on  the  Macacus  monkey  under  good 
conditions  and  with  anatomical  control  by  Ferrier  and  Turner. 
Immediately  after  the  operation  the  animal  cannot  maintain  its 
equilibrium,  it  remains  lying  upon  its  stomach,  the  limbs  of  the 
operated  side  flexed  and  in  adduction,  and  those  of  the  opposite 
side  extended  and  in  abduction.  This  attitude,  howev.er,  may 
not  be  constant,  all  four  limbs  may  be  in  abduction ;  all  attempts 
to  stand  up  and  to  move  are  followed  by  falls  on  the  operated 
side  and  a  tendency  to  roll  in  that  direction.  In  its  cage  the 
monkey  grips  the  bars  with  the  limbs  of  the  healthy  side,  in  order 
to  avoid  a  fall  on  the  side  of  the  injury.  It  is,  however,  still 
capable  of  climbing  vigorously  by  using  its  four  limbs.  Nys- 
tagmus is  inconstant;  when  it  is  present  it  is  more  marked  in 
the  eye  of  the  injured  side,  and  when  looking  in  that  direction. 
Gradually  the  animal  becomes  more  stable,  preserving,  however, 
the  same  tendency  to  fall  towards  the  side  of  the  lesion ;  it  wavers 
and  balances  its  body.  During  the  first  days  it  is  not  able  to 
maintain  the  position  of  sitting  up,  at  any  rate,  not  unless  it  is 
assisted. 

From  the  beginning  the  limbs  of  the  operated  side  tremble 
as  a  result  of  effort  and  of  volitional  movement.  The  tremor  is 
comparable  to  that  of  multiple  sclerosis.  The  animal  takes  food 
more  readily  with  the  hand  of  the  side  which  is  uninjured. 


IOO  THE    FUNCTIONS    OF    THE    CEREBELLUM 

Fifteen  days  later  the  disturbances  of  equilibrium  have  almost 
entirely  disappeared.  The  animal  does  not  fall  unless  it  turns 
around  or  executes  movements  too  suddenly ;  it  can  sit  up  without 
holding  on  to  anything. 

A  Macacus  which  Ferrier  kept  for  forty  days  after  the  opera- 
tion did.  not  fall  towards  the  end,  unless  it  were  jostled;  the 
tremor  of  the  superior  and  inferior  limbs  persisted  to  the  end,  as 
did  the  nystagmus. 

Summarizing,  the  troubles  following  section  of  the  superior 
cerebellar  peduncle  are  as  follows:  Uncertainty  of  equilibrium, 
falls,  and  a  tendency  to  roll  on  the  side  operated,  intention  tremor 
of  the  same  side  and  a  permanent  nystagmus.  The  tendon  re- 
flexes are  equal  on  both  sides. 


CHAPTER  V 

SYMPTOMATOLOGY   OF   THE   AFFECTIONS   OF   THE 
CEREBELLUM 

In  man  the  symptomatology  of  the  affections  of  the  cerebellum 
corresponds  to  the  phenomena  noted  after  experimental  destruc- 
tions in  animals.  However,  all  the  clinical  observations  cannot 
be  used  in  this  way  for  a  physiological  demonstration.  Only 
those  should  be  retained  which  by  the  precise  determination  of 
the  nature  and  of  the  localization  of  the  lesion,  have  the  value  of 
a  true  experiment.  Consequently,  we  must  eliminate  all  those 
complex  cases  wherein  the  lesion,  although  not  exceeding  the 
limits  of  the  cerebellum,  is  nevertheless  susceptible  by  its  nature 
of  compromising  the  functions  of  neighboring  centers.  This  is 
the  case  in  a  large  number  of  abscesses  and  tumors  of  the  cere- 
bellum, without  taking  account  of  the  fact  that  in  these  cases  the 
cerebellar  symptoms  may  raise  some  difficulty  of  interpretation, 
and  may  be  looked  upon  as  phenomena  of  excitation  or  as  phe- 
nomena of  defect. 

It  is  preferable  to  consider  separately  the  observations  in 
which  the  cerebellar  lesions  have  commenced  suddenly  (hemor- 
rhages, softening)  and  those  in  which  the  lesions  have  had  a  slow 
and  progressive  evolution.  Only  the  first  class  can  be  rigorously 
compared  to  destructions  performed  upon  animals.  In  both 
cases  there  is  a  sudden  suppression  of  the  organ  and  of  its 
functions. 

Finally,  one  must  establish  clinical  differences  as  to  whether 
the  lesion  is  cortical  or  central,  or  both. 

I.  HEMORRHAGE  OR  SOFTENING 

The  symptomatology  of  hemorrhagic  foci,  or  foci  of  softening 
of  the  cerebellum,  is  very  slightly  known  for  two  reasons.  The 
anatomical  examinations  are  generally  incomplete,  and  it  is  im- 
possible to  affirm  that  the  symptoms  are  exclusively  localized  in 
the  cerebellum.  Many  observations  have  been  published  simply 


IO2  THE    FUNCTIONS    OF    THE    CEREBELLUM 

as  findings  at  the  autopsy,  that  is  to  say,  as  having  given  rise  to 
no  symptoms  during  life.  One  may  note,  a  propos  of  this  sub- 
ject, that  it  is  more  often  than  not  impossible  to  fix  the  date  of 
the  commencement  of  the  softening,  and  that,  perhaps,  several 
months  or  even  several  years  have  elapsed  since  the  commence- 
ment of  the  lesion  and  the  observation  of  the  person  who  makes 
the  examination,  and  that  the  symptoms  may  have  had  time  to 
have  completely  disappeared,  or  nearly  so. 

Only  those  observations,  followed  by  an  histological  examina- 
tion made  upon  a  series  of  sections,  have  any  real  documentary 
value,  as  well  from  the  physiological  as  from  the  anatomical  point 
of  view.  How  is  it  possible  to  give  a  physiological  signification 
to  any  observation  if  one  is  unable  to  affirm  that  the  lesions  are 
strictly  localized  in  the  cerebellum  and  do  not  trench  upon  the 
neighboring  centers?  The  case  published  by  V.  Negel  and  A. 
Theohari  is  an  example  in  point.  The  patient  who  was  the  sub- 
ject of  this  observation  presented  disturbances  of  upright  station, 
of  gait,  and  of  speech,  dating  back  some  six  weeks  before  the 
time  of  his  first  examination.  The  body  oscillated  in  an  antero- 
posteriqr  direction ;  when  the  patient  passed  from  the  dorsal 
decubitus  to  a  seated  position,  he  had  a  very  manifest  tendency 
to  fall  backwards;  during  walking  the  base  of  support  was  very 
much  enlarged.  The  upper  and  lower  limbs  were  affected  by 
tremors  during  the  execution  of  movements.  The  voice  was 
nasal  and  words  were  emitted  with  suddenness.  During  the  last 
days  the  patient  fell  into  a  comatose  condition  and  all  of  the  mus- 
cles were  in  a  state  of  marked  stiffness.  The  autopsy  revealed 
a  focus  of  softening  in  the  left  cerebellar  hemisphere,  which 
involved  the  white  substance  and  the  dentate  nucleus.  An  histo- 
logical examination  upon  a  series  of  sections  showed,  besides 
some  other  small  foci  situated  in  the  left  superior  cerebellar 
peduncle,  the  median  fillet  of  Reil,  the  posterior  longitudinal 
fasciculus,  and  the  central  bundle  of  the  tegmentum ;  another  in- 
volved the  pyramidal  bundle  of  the  same  side,  and  still  another 
one  the  path  of  the  right  fillet  of  Reil. 

To  summarize :  These  symptoms  were  incontestably  those  of 
a  cerebellar  lesion  and  the  principal  lesion  was  situated  in  the  cere- 
bellum. However,  some  of  the  lesions  were  in  the  paths  of  the 
cerebellar  tracts.  If,  however,  one  wishes  to  proceed  to  an  inter- 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          1 03 

pretation  in  a  rigorously  scientific  manner,  one  cannot  but  take 
into  account  the  interruption  of  the  other  bundles,  of  which  there 
would  have  been  no  question  had  not  the  authors  made  a  consci- 
entious anatomical  examination  of  the  case. 

The  principal  symptoms  of  foci,  of  softening  or  hemorrhage 
of  the  cerebellum  are :  Titubation,  with  a  widening  of  the  base 
of  support,  disturbances  of  equilibrium,  falls  to  the  side  or  back- 
ward, according  as  the  focus  is  situated  in  a  hemisphere  or  in 
the  vermis,  an  intention  tremor  or  clonic  movements  of  the 
upper  limbs,  sudden  but  non-ataxic  movements  of  the  lower  limbs 
and  rapid  fatigue.  As  less  constant  phenomena,  vertigo,  ocular 
disturbances  and  nystagmus. 

The  symptoms  of  onset  are  less  well  known ;  apoplexy  is  usual, 
and  vomiting  has  been  frequently  noted.  On  the  other  hand,  move- 
ments of  rotation  or  rolling,  analogous  to  those  which  are  pro- 
duced in  animals  after  the  destruction  of  the  cerebellar  hemi- 
sphere, are  exceptional.  They  are  mentioned  in  an  observation 
of  Meschede.  The  patient  had  movements  of  locomotion,  re- 
peated in  a  determinate  direction,  affecting  an  impulsive  form. 
Sudden  goings  and  comings,  movements  in  a  circle,  movements 
around  the  longitudinal  axis,  always  from  the  left  to  right;  the 
gait  was  also  oscillating,  the  movements  of  the  limbs  awkward, 
and  speech  halting.  The  right  cerebellar  hemisphere  was  atro- 
phied.1 It  is  more  common  to  see  patients  drawn  laterally  in  the 
direction  of  the  lesion,  and  consequently,  to  describe  a  sort  of  cir- 
cular movement. 

The  symptoms  predominate  or  only  exist  on  the  injured  side. 
Some  cases  are  noted  of  a  unilateral  paralysis  or  paresis,  in  direct 
relation  to  the  cerebellar  lesion.  But  is  the  paralysis  really  due 
to  the  destruction  of  a  part  of  the  cerebellum?  Is  it  not  rather 
the  consequence  of  a  concomitant  lesion  in  another  region  of  the 
encephalon?  In  several  cases  of  hemiplegia  I  have  found  at  the 
autopsy  a  focus  of  softening  in  the  cerebellum,  but  on  making 
an  histological  examination  of  the  lesions  and  degenerations  in  a 
series  of  sections,  I  have  found  similar  foci  in  the  pons,  and  on 

1  Serres  observed  a  patient  who  turned  around  himself  from  right  to 
left,  and  the  lesion  was  found  in  the  right  peduncle  of  the  cerebellum. 
Belhomme  also  observed  movements  of  rotation  to  the  right  in  a  patient 
in  whom  the  left  cerebellar  peduncle  was  compressed  by  an  exostosis. 


1O4  THE    FUNCTIONS    OF    THE    CEREBELLUM 

the  path  of  the  cortical  motor  tract.  This  condition  is  far  from 
being  exceptional. 

To  summarize:  The  symptomatology  of  hemorrhages  or  sof- 
tenings of  the  cerebellum  is  still  quite  doubtful.  It  comprises 
disturbances  of  locomotion,  of  equilibrium,  of  motility  of  the 
limbs,  and  sometimes  disturbances  of  speech.  What  relations 
exist  between  the  seat  of  the  focus  and  the  clinical  picture? 
What  is  the  duration  of  the  symptoms?  Are  there  quantitative 
or  qualitative  differences,  according  as  to  whether  the  lesion 
affects  the  cortex,  the  white  substance,  or  the  central  gray  nuclei  ? 
So  many  questions  await  a  precise  rigorously  scientific  solution. 
Certainly  limited  foci  in  the  cortex  are  more  silent  than  those 
which  cover  a  large  surface  of  the  cortex,  or  than  central  foci 
affecting  the  gray  nuclei  and  the  peduncles.  But  many  of  the 
notions  which  we  have  of  this  subject  are  still  vague  and  undecided. 

The  majority  of  authors  do  not  admit  that  lesions  of  the  cere- 
bellum can  produce  homolateral  or  direct  hemiplegia  (v.  Monakow, 
Bruns,  and  Oppenheim).  Contrary  to  this  opinion,  Mann  de- 
scribed a  cerebellar  hemiplegia  which  is  distinguished  from  a 
cerebral  hemiplegia :  First,  by  the  fact  that  it  affects  all  of  the 
muscles,  whereas,  in  a  cerebral  hemiplegia,  certain  groups  only 
are  affected  more  than  others  (dorsal  flexors  of  the  foot,  flexors 
of  the  leg,  extensors  of  the  hand,  external  rotators  of  the  arm, 
etc.);  second,  the  absence  of  contraction;  third,  a  simple  exag- 
geration of  the  reflexes  without  spasticity,  the  absence  of  epilep- 
toid  trepidation,  and  of  the  Babinski  sign. 

This  opinion  is  based  upon  observation  and  arguments,  the 
value  of  which  will  be  discussed  further  on. 

II.   AGENESES  OF  THE  CEREBELLUM 

The  congenital  atrophies  of  the  cerebellum,  or,  better,  ageneses, 
are  rarely  total.  Either  there  is  a  lack  of  a  cerebellar  hemisphere 
or  the  cerebellum  exists  with  a  configuration  resembling  the 
normal,  but  reduced  in  all  its  dimensions. 

Generally  speaking,  the  clinical  expression  of  these  ageneses  is 
very  slightly  marked,  compared  to  atrophies  developed  in  the  adult 
or  with  tumors ;  sometimes  there  are  no  clinical  symptoms  at  all. 

In  a  case  of  almost  total  agenesis  of  the  right  hemisphere  of 
the  cerebellum,  Neuburger  and  Edinger  observed  no  disturbance 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          1 05 

which  allowed  them  to  suppose  the  existence  of  a  cerebellar 
lesion.  "  There  was  no  incertitude  in  the  gait  or  the  station ;  no 
weakness  of  the  extremities,  no  nystagmus,  no  disturbances  of 
speech,  no  vertigo,  etc. ;  it  was  only  noted  that  during  infancy  and 
adolescence,  the  head  was  often  turned  to  the  left,  and  oscil- 
lated." The  right  hemisphere  was  almost  entirely  lacking;  it 
was  about  the  size  of  a  walnut,  but  of  an  entirely  normal  con- 
sistence and  possessed  well-formed  convolutions.  The  vermis 
was  altogether  normal. 

In  a  case  of  total  agenesis  of  a  cerebellar  hemisphere,  Nonne 
also  observed  no  disturbance  whatever. 

A  patient  examined  by  Andral  was  incapable  of  doing  the 
slightest  thing  that  required  application  or  dexterity.  If,  for  ex- 
ample, she  undertook  any  delicate  work,  she  was  immediately 
seized  with  a  convulsive  tremor  of  the  hand.  She  was  always 
afraid  of  falling  when  she  walked.  Her  step  was  not  certain. 
She  was  strong,  robust,  capable  of  lifting  heavy  burdens,  but  a 
feeble-minded  imbecile.  The  left  hemisphere  of  the  cerebellum 
was  altogether  wanting,  and  in  its  place  a  sort  of  stump  or  tubercle 
was  found.  There  was  nothing  abnormal  in  the  cerebrum  or  the 
meninges.  In  this  case  a  complete  anatomical  examination  was 
not  made. 

A  patient  observed  by  Lallemant  presented  only  a  slowness  of 
gait.  The  left  cerebellar  hemisphere  was  reduced  to  a  small  mass 
about  the  size  of  a  hazel  nut,  attached  to  the  lateral  portions  of 
the  pons. 

A  patient  examined  by  Hitzig  had  no  motor  disturbances  up 
to  the  age  of  thirty-two.  She  had  learned  to  walk  at  the  regular 
time  and  could  jump  and  dance.  It  was  only  after  attaining  the 
age  of  thirty-two  that  symptoms  supervened  which  must  be 
attributed  to  tabes  and  general  paralysis.  The  right  cerebellar 
hemisphere  was  reduced  to  two  small  lobules  about  the  size  of 
a  bean. 

Among  the  observations  of  total  absence  of  the  cerebellum, 
that  of  Combettes  is  the  most  celebrated.  The  cerebellum  was 
represented  by  two  small  masses  of  white  substance,  having  the 
volume  of  a  pea.  The  cerebrum  and  the  spinal  cord  appeared 
to  be  normal.  The  little  patient  had  only  lived  for  thirteen  years. 
She  developed  very  slowly  and  was  backward  from  every  point 


IO6  THE    FUNCTIONS    OF    THE    CEREBELLUM 

of  view.  She  spoke  with  difficulty  and  with  hesitation.  Her 
legs,  although  very  weak,  were  sufficiently  strong  for  her  to  walk, 
but  she  fell  frequently.  She  could  use  her  hands  with  ease. 

Anton  observed  a  patient  very  comparable  to  the  one  of  Com- 
bettes.  It  was  the  case  of  a  little  girl  six  years  old,  all  of  whose 
movements  were  slow  and  incomplete.  She  did  tiot  commence 
to  sit  up,  to  stand  up  and  to  walk  until  after  she  was  four  years 
old.  She  was  unable  to  walk  or  to  hold  herself  upright  except 
by  holding  on  to  something.  The  movements  of  her  legs  were 
incoordinate.  She  staggered  and  fell  frequently.  The  move- 
ments of  the  arms  were  slow  and  somewhat  incoordinated.  Fa- 
tigue supervened  rapidly.  Speech  was  not  very  clear,  but  there 
was  no  sign  of  tremor  in  the  writing.  The  patellar  reflexes  were 
exaggerated.  At  the  autopsy  there  was  a  total  absence  of  the 
cerebellum. 

In  the  case  of  a  patient  of  Verdelli,  nineteen  years  of  age, 
the  cerebellum  was  almost  as  much  atrophied  as  in  the  patient  of 
Combettes.  Unfortunately,  rachitic  deformities  of  the  skeleton 
and  lower  limbs  prevented  a  study  of  the  gait.  The  patient  stam- 
mered. He  was  able  to  use  his  arms  with  facility  and  they  were 
strong  enough  to  support  the  weight  of  his  body  upon  crutches. 

There  was  also  a  total  absence  of  the  cerebellum  in  a  patient 
of  Shuttleworth's,  fifteen  years  of  age.  A  great  general  muscu- 
lar weakness  had  been  observed,  combined  with  a  tremor  of  the 
hands  and  arms.  Besides,  there  was  a  very  pronounced  arrest  of 
intellectual  development. 

An  observation  of  Otto  must  be  ranked  in  the  group  of  partial 
ageneses.  Clinically  there  was  nothing  particular  to  be  noted 
except  that  the  movements,  forcible  and  dextrous,  were  febrile 
and  impulsive.  The  cerebellum  was  very  small.  It  was  five 
centimeters  wide  and  three  centimeters  at  its  greatest  depth. 
(This  was  the  case  of  a  man  thirty-nine  years  old.)  The  micro- 
scopic examination  showed  that  this  little  organ  was  composed  of 
absolutely  normal  elements. 

The  results  of  an  examination  of  a  boy  with  an  epileptic  psy- 
chosis reported  by  Borell,  and  in  whom  speech  and  walking  be- 
came difficult  from  the  age  of  ten  years,  is  as  follows  :  Movements 
were  difficult  and  awkward,  particularly  of  the  tegs.  There  was 
a  bending  of  all  parts  of  the  body  during  walking,  as  if  they  were 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          IO/ 

attached  together  only,  by  loose  ligaments.  The  feet  interfered 
with  one  another.  When  he  ran  he  manifested  a  certain  degree 
of  fear  and  turned  his  right  side  forward.  He  oscillated  when 
he  stood  up  in  order  to  preserve  his  equilibrium.  Speech  was 
slow  and  scanning.  The  cerebellum  was  very  small.  The  left 
hemisphere  was  completely  lacking.  The  largest  diameter  of  the 
right  hemisphere  was  twenty-eight  millimeters,  and  the  vermis 
was  very  much  reduced  in  size. 

These  observations  of  ageneses  of  the  cerebellum  are  far  from 
giving  concordant  results.  .  To  consider  them  only  from  a  physio- 
logical point  of  view,  one  cannot  but  be  surprised  to  learn  that  a 
unilateral  agenesis  so  complete  as  that  related  by  Neuburger  and 
Edinger  had  a  clinical  evolution  of  so  silent  a  character.  The 
total  ageneses  of  the  cerebellum  have  a  more  marked  symptoma- 
tology than  the  unilateral  ageneses.  In  the  majority  of  the  obser- 
vations motor  disturbances  have  been  mentioned,  but  they  have 
been  insufficiently  described. 

III.   ATROPHIES  OF  THE  CEREBELLUM 

The  cases  of  primitive  atrophy  of  the  cerebellum  of  a  slow 
and  progressive  evolution  form  a  very  important  group.  Among 
the  observations  of  these  cases,  however,  there  are  very  few  that 
are  physiologically  utilizable,  because  along  with  the  systemic 
lesions  of  the  cerebellum  there  are  also  systemic  lesions  of  other 
organs,  particularly  of  the  spinal  cord.  An  exception  should  be 
made  in  the  case  of  olivo-ponto-cerebellar  atrophy,  of  which  we 
have  published  either  alone  or  with  M.  Dejerine  several  observa- 
tions followed  by  autopsies.  The  one  which  we  examined  with 
M.  Dejerine  is  the  only  one  in  which  the  atrophies  and  degenera- 
tions were  strictly  localized  in  the  cerebellum :  The  pons  and  par- 
ticularly the  anterior  layer  and  the  olives  were  equally  atrophied, 
but  these  are  organs  which  enter  into  direct  relation  with  the 
cerebellum. 

The  following  is  a  list  of  the  anatomical  lesions:  (i)  A  sym- 
metrical atrophy  of  the  cerebellar  cortex  more  pronounced  in  the 
hemisphere  than  in  the  vermis,  and  contrasting  with  a  relative 
integrity  of  the  central  gray  nuclei,  i.  e.,  the  dentate  nucleus,  the 
nucleus  of  the  roof,  the  globulus  and  the  embolus  (Figs.  56  and 
57)  ;  (2)  total  atrophy  *of  the  gray  substance  of  the  pons  and 


io8 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


total  degeneration  of  the  middle  cerebellar  peduncle  (Fig.  58). 
The.  superior  cerebellar  peduncle,  which  takes  its  origin  in  the 
dentate  nucleus,  was,  on  the  other  hand,  relatively  well  preserved. 


57 

FIGS.  56  and  57.  Lesions  of  the  cerebellum  in  a  case  of  olive-ponto- 
cerebellar  atrophy.  Atrophy  of  the  cortex  and  degeneration  of  the  white 
substance.  Integrity  of  the  central  gray  nuclei  and  of  the  superior  cere- 
bellar peduncle.  Atrophy  of  the  medullary  olives  and  the  restiform  body. 
(J.  Dejerine  and  Andre-Thomas,  Iconographie  de  la  Salpetrlere,  1900.) 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM 


(3)  A  very  pronounced  atrophy  of  the  inferior  olives,  of  the 
accessory  olivary  nuclei,  and  of  the  arciform  nuclei,  and  a  degen- 
eration of  the  external  arciform  fibers  and  of  the  restiform  body. 
The  pyramids  and  the  cerebral  peduncles  appeared  smaller  than 
normal,  but  without  any  trace  of  degeneration. 

The  lesions  of  the  cerebellar  cortex  were  essentially  charac- 
terized by  the  disappearance  of  most  of  the  Purkinje  cells. 

Clinically  the  movements  of  the  body  as  a  whole  were  pro- 
foundly altered,  whether  they  took  place  in  the  seated  or  in  the 
upright  position,  whether  the  patient  walked  or  passed  from  the 
seated  position  to  a  position  lying  down,  or  from  a  position  lying 


FIG.  58. 


Same  case  as  Figs.  56  and  57.    Atrophy  of  the  anterior  surface 
of  the  pons  and  the  middle  cerebellar  peduncles. 


down  to  a  position  standing.  All  these  changes  of  attitude  were 
executed  with  slowness,  hesitation,  uncertainty  and  awkwardness. 
A  fall  was  sometimes  the  consequence  of  this  disequilibration. 

Upon  rising  the  body  was  agitated  by  oscillations  and  the 
patient  could  not  pass  from  the  seated  to  the  standing  position 
without  holding  on  to  some  neighboring  object. 

In  the  upright  position  the  feet  were  spread  wide  apart,  the 
base  of  support  enlarged ;  the  elbows  were  held  in  abduction  and 
the  body  was  the  seat  of  either  antero-posterior  or  transverse 
oscillations.  The  patient  had  the  sensation  that  he  was  about  to 
fall  forward.  Upright  station  with  the  feet  close  together  was 
difficult,  if  not  impossible. 


I  IO  THE    FUNCTIONS    OF    THE    CEREBELLUM 

In  walking  the  lower  and  upper  limbs  preserved  the  same 
position.  The  patient  walked  with  caution  as  if  seeking  his  equi- 
librium. Each  foot  was  only  lifted  after  hesitation,  but  then  sud- 
denly and  replaced  in  the  same  manner.  The  steps  were  short 
and  irregular  and  described  a  wavy  line,  because  the  body  was 
carried  either  too  far  forward  or  backward,  or  to  the  side,  and 
oscillated. 

Summary. — There  are  no  traces  of  the  rhythm  or  of  the 
cadence  of  the  normal  gait.  Fatigue  supervenes  rapidly.  The 
disturbances  of  station  and  of  locomotion  are  hardly  augmented 
by  covering  the  eyes,  consequently  there  was  no  Romberg  sign. 

The  isolated  movements  of  the  upper  and  lower  limbs,  con- 
trasted in  their  relative  integrity  with  this  considerable  perturba- 
tion of  equilibration. 

In  the  upper  limbs  there  was  no  trace  of  paralysis.  Resist- 
ance to  passive  movements  of  flexion  and  extension  was  very 
great.  The  limbs  could  be  stretched  out,  the  forearm  on  the  arm, 
the  hands  from  the  forearm  and  the  fingers  spread  apart  without 
any  oscillation  of  the  limbs  or  manifest  trembling  of  the  fingers. 
In  spite  of  that,  motility  was  not  absolutely  intact,  when  the 
patient  seized  or  moved  a  heavy  object  she  became  awkward. 
The  movements  were  slow  and  hesitating.  When  the  patient 
tried  to  fill  a  glass  the  hand  which  held  the  bottle  oscillated  and 
poured  the  liquid  to  one  side.  The  writing  was  shaky,  the  letters 
irregular  and  unequally  spaced,  and  some  of  them  unrecognizable, 
notwithstanding  the  characters  were  written  slowly,  the  patient 
taking  great  pains  to  trace  them. 

Motility  was  not  disturbed  in  the  lower  limbs;  all  the  move- 
ments executed  in  bed  were  correct. 

The  limbs  and  segments  of  limbs  could  be  placed  in  abnormal 
attitudes.  Consequently  there  was  no  hypertonus.  Sensibility 
in  all  its  modes,  superficial  and  deep,  was  intact.  There  was 
neither  paralysis  nor  muscular  atrophy. 

The  movements  of  the  head  were  slow.  The  same  slowness 
was  found  in  the  movements  of  the  face  (elevation  of  the  lips, 
opening  of  the  mouth,  and  the  action  of  making  a  grimace).  The 
physiognomy  was  almost  without  expression.  The  ability  to 
mimic  very  slight.  Neither  the  tongue  or  the  palate  were  para- 
lyzed. In  spite  of  that  speech  was  slow,  drawling  and  slightly 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          I  I  I 

scanning.  All  isolated  and  synergic  movements  of  the.  eyes  were 
normally  executed  except  elevation,  which  was  done  in  several 
stages.  This  was  rather  a  series  of  nystagmiform  shocks  than 
true  nystagmus. 

The  tendon  reflexes  were  exaggerated,  but  there  was  no 
sign  which  indicated  a  disturbance  of  the  pyramidal  tract  (signs 
of  Babinski,  or  of  Oppenheim,  epileptoid  trepidation,  etc.). 

Similar  phenomena  were  observed  by  the  same  authors  in  an- 
other patient,  but  without  anatomical  verification.  I  only  cite  them 
in  comparison  and  not  as  evidence  of  equal  value.  The  disturb- 
ances of  equilibrium  were  of  the  same  nature.  They  were  exag- 
gerated upon  a  change  of  attitude.  In  walking  the  patient  gave 
the  impression  rather  of  having  lost  his  balance  than  of  walking 
like  a  drunken  man.  The  upper  limbs  were  awkward.  "When 
the  patient  wished  to  seize  an  object,  a  glass,  for  example,  he 
grasped  too  suddenly.  When  he  tried  to  lift  it  to  his  mouth  he 
hesitated  a  little,  he  was  not  sure  of  holding  it  well,  and  there 
were  some  small  lateral  movements  which  prevented  the  hand 
from  accomplishing  the  desired  object.  The  patient  said  himself 
that  he  was  more  awkward  with  his  hands,  and  it  very  often  hap- 
pened that  he  upset  objects  at  the  moment  of  taking  hold  of 
them  or  carrying  them."  The  same  disturbances  of  speech,  nys- 
tagmus and  exaggeration  of  reflexes,  etc.,  were  found  in  him. 

These  observations,  of  which  one  was  followed  by  a  rigorous 
anatomical  control,  clearly  show  the  influence  of  the  cerebellum 
upon  the  equilibration  of  the  body  in  general,  and  also  upon  the 
motility  of  the  limbs.  We  will  see  further  what  physiological 
interpretation  we  may  give  to  these  various  symptoms. 

There  exists  in  the  literature  a  number  of  observations  of 
atrophy  of  the  cerebellum.  It  is  to  be  regretted  that  one  cannot 
give  a  collective  description  of  them,  but  the  observations  are  not 
sufficiently  superposable  to  enable  one  to  do  so  without  reserve. 
One  must  be  contented  with  an  exposition  of  the  facts;  the  facts 
are  few,  and  in  reading  a  resume  of  some  of  those  which  are 
ordinarily  cited  as  the  most  convincing,  one  will  perceive  that 
this  chapter  is  far  from  being  conclusive,  at  least,  unless  one  sac- 
rifice rigorously  scientific  methods,  and  is  more  content  with  im- 
pressions than  with  exactness. 

In  two  other  observations  of  olivo-ponto-cerebellar  atrophy, 


112  THE    FUNCTIONS    OF    THE    CEREBELLUM 

followed  by  autopsies  and  reported  in  my  thesis,  I  observed 
symptoms  of  the  same  type  as  in  the  preceding  observations,  but 
in  one  of  these  cases  the  columns  of  the  spinal  cord  were  only 
slightly  degenerated,  and  in  the  other  the  degenerations  were  more 
extended,  occupying  the  posterior  columns,  the  direct  cerebellar 
tract,  and  the  tract  of  Cowers. 

Pierret,  Menzel,  Royet  and  Collet,  and  Arndt,  in  their  obser- 
vations mention  not  only  disturbances  of  equilibrium  and  gait,  but 
also  incoordination,  or  intention  tremor.  However  these  lesions 
were  not  exclusively  distributed  in  the  cerebellum  and  the  parts 
dependent  upon  them :  the  bundles  of  the  spinal  cord,  and  more 
particularly  the  pyramidal  tract  and  the  posterior  columns  were 
partly  degenerated  (observations  of  Menzel  and  Arndt).  The 
patient  of  Pierret  had  tremors  of  the  arms,  although  the  spinal 
cord  was  intact.  In  the  patient  of  Royet  and  Collet  the  arms 
were  affected  by  a  slight  tremor  when  in  extension  with  the 
fingers  spread  apart,  or  when  it  was  attempted  to  raise  an  object  to 
the  mouth ;  the  objects  were  carried  to  their  destination  practically 
in  a  direct  manner,  but  with  some  oscillation ;  but  the  anatomical 
examination  does  not  appear  to  have  been  complete.  In  all  of 
these  patients  disturbances  of  speech  were  noted,  diversely  de- 
scribed, according  to  the  authors  (embarrassment  of  speech,  slow 
speech,  hesitating,  uncertain,  etc.). 

The  observation  of  Eraser  concerns  a  case  of  cerebellar 
atrophy,  but  unfortunately  from  the  anatomical  point  of  view  it 
is  very  incomplete.  Equilibrium  and  motility  of  the  limbs  were 
both  compromised :  "  When  one  asked  the  patient  to  seize  an 
object  he  acted  like  a  choreaic,  although  to  a  less  marked  degree. 
After  having  seized  the  object  he  could  hold  it  at  arm's  length 
without  tremor  or  hesitation ;  asked  to  touch  the  end  of  his  nose 
with  his  finger,  he  could  do  it  almost  as  well  as  a  normal  indi- 
vidual, although  he  hesitated  slightly." 

The  observation  of  Nonne  has  a  more  difficult  interpretation. 
The  atrophy  of  the  cerebellum  appeared  to  be  due  to  an  arrest 
of  development.  The  encephalon  was  smaller  than  a  normal 
encephalon.  "  The  patient  was  able  to  dress  himself  alone  but 
with  such  pains  and  so  slowly  that  he  was  usually  assisted.  He 
was  able  to  eat  by  himself  also  but  not  without  spilling  his  food. 
It  was  particularly  during  attempts  at  writing  that  the  disturb- 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          I  I  3 

ances  of  motility  appeared.  During  walking  the  foot  was  lifted 
from  the  ground  in  an  incoordinate  manner,  but  he  did  not 
replace  the  heel  first  nor  did  he  throw  the  legs  forward  like  an 
ataxic." 

The  observation  of  Miura  may  be  compared  to  that  of  Nonne. 
From  the  triple  point  of  view — anatomical,  clinical,  etiological  (in 
both  cases  heredity  and  family  characteristics  were  found).  The 
first  symptoms  appeared  at  the  age  of  twenty-five.  The  gait  be- 
came gradually  uncertain;  the  body  vacillated  and  described  oscil- 
lations during  walking;  the  hands  were  equally  clumsy.  When 
the  patient  was  examined  by  Miura  disturbances  of  gait  and  equi- 
librium, incertitude  of  the  extremities  in  all  actions,  and  visual 
disturbances  were  noticeable.  Progression  was  not  made  in  a 
straight  line,  the  body  was  carried  first  too  much  to  the  right, 
then  too  much  to  the  left,  and  sometimes  even  backward,  so  that 
he  was  threatened  with  a  fall.  The  hands  did  not  tremble,  never- 
theless, writing  revealed  great  uncertainty  and  a  manifest  ataxia 
of  the  hands.  With  the  arms  widely  separated  the  patient  could 
touch  his  two  index  fingers  together,  as  well  with  the  eyes  shut 
as  with  them  open.  Speech  was  explosive,  badly  articulated  and 
scanning,  sometimes  hardly  comprehensible.  There  was  a  slight 
horizontal  nystagmus.  In  the  upright  position  the  legs  were 
spread  wide  apart  and  the  big  toes  in  hyperextension ;  the  body 
was  animated  with  oscillations  which  were  not  much  augmented 
by  the  closure  of  the  eyes.  The  tendon  reflexes  were  normal; 
the  same  was  the  case  for  deep  and  superficial  sensation.  On 
the  other  hand,  there  were  serious  disturbances  of  vision  (dimi- 
nution of  visual  acuity,  the  disks  were  injected  and  not  well  lim- 
ited, and  the  pupillary  reflexes  to  light  and  accommodation  were 
sluggish). 

At  the  autopsy  the  cerebellum  was  found  to  be  small,  only 
weighing  80  grams,  the  white  and  gray  substances  were  less  devel- 
oped than  in  a  normal  individual,  but  they  were  well  proportioned 
to  one  another.  Compared  to  a  normal  cerebellum,  the  fibers  of 
the  white  substance  and  their  ramifications  in  the  lobules  and 
lamellae  were  spaced  further  apart.  But  this  was  not  all ;  the 
cerebro-spinal  axis  was  smaller  than  normal.  This  reduction  in 
size  was  particularly  remarkable  in  the  spinal  cord.  The  cerebral 
convolutions,  however,  were  also  atrophied.  The  peripheral 


114  THE    FUNCTIONS    OF    THE    CEREBELLUM 

nerves  were  also  degenerated.  (The  patient  was  at  the  same  time 
affected  with  kakke,  or  beri-beri.)  The  two  retinae  showed  some 
lesions.  One  cannot,  therefore,  without  reserve  put  down  all 
these  symptoms  observed  in  this  patient  of  Miura  to  the  account 
of  cerebellar  atrophy. 

In  the  patient  examined  by  Schultze,  there  were  besides  the 
disturbances  of  equilibrium  during  walking  and  standing,  dis- 
turbances of  speech  and  traces  of  intention  tremor  in  the  arms, 
as  well  as  nystagmus.  The  lesions  consisted  of  an  atrophy  of  the 
cerebellum  affecting  not  only  the  cortex  but  also  the  dentate 
nucleus,  which  was  very  much  compromised ;  besides,  the  medul- 
lary pyramids  were  slightly  colored  (method  of  Pal),  and  in  the 
spinal  cord  the  crossed  pyramidal  tracts  were  degenerated. 

In  some  cases  atrophy  of  the  cerebellum  presents  itself  in  a 
more  striking  form.  The  atrophy  does  not  affect  equally  all  of 
the  lobes,  lobules  and  lamellse;  it  affects  irregularly  certain  la- 
mellae and  other  neighboring  lamellse  may  be  absolutely  untouched. 
In  the  affected  lamellae  the  cells  of  Purkinje  completely  disappear 
and  are  replaced  by  a  thick  felt-work  of  neuroglia. 

In  one  of  these  cases  which  I  have  studied  under  the  name  of 
lamellar  atrophy,  the  disturbances  of  equilibrium  during  the  up- 
right position  were  of  a  distinct  character.  The  description  is 
as  follows:  During  walking  the  legs  are  spread  wide  apart,  the 
base  of  support  is  very  much  widened,  the  toes  are  manifestly 
directed  outwards,  the  arms  are  in  marked  abduction.  The  pa- 
tient walks  distinctly  upon  her  heels,  but  she  does  not  throw  her 
legs  forward  like  an  ataxic.  She  does  not  follow  a  straight  line, 
but  describes,  in  walking,  a  broken  one,  the  body  being  carried 
alternately  too  much  to  the  right  or  too  much  to  the  left.  In 
spite  of  that  the  general  direction  towards  the  goal  is  preserved. 
At  the  same  time  the  body  is  constantly  the  seat  of  antero- 
posterior  and  lateral  oscillations,  and  the  patient  constantly  looks 
at  the  ground  seemingly  preoccupied  in  reestablishing  her  equi- 
librium, or  at  least  in  avoiding  the  loss  of  it.  The  closing  of  the 
eyes  does  not  sensibly  augment  the  disturbances  of  equilibrium 
during  the  upright  position  or  in  walking,  on  condition  that  the 
feet  remain  spread  apart;  as  soon  as  they  are  approached  to  one 
another  she  cannot  stand  upright,  and  as  soon  as  the  control  of 
sight  is  suppressed  she  is  threatened  with  a  fall.  She  is  also 
unable  to  support  herself  on  one  foot. 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM 


Il6  THE    FUNCTIONS    OF    THE    CEREBELLUM 

The  arms  are  not  at  all  affected.  Their  muscular  force  and 
sensibility  are  intact.  There  is  neither  ataxia  nor  intention 
tremor.  The  olecranon  and  radial  reflexes  are  normal.  In  con- 
trast, the  movements  of  the  legs  are  irregular.  They  are  accom- 
panied by  an  intention  tremor  analogous  to  that  of  multiple 
sclerosis.  This  irregularity  cannot  be  put  entirely  to  the  account 
of  the  cerebellar  lesion.  There  is  also  a  double  club  foot,  the 
remains  of  an  infantile  paralysis,  the  lesion  of  which  was  easily 
found  at  the  autopsy. 

Two  similar  observations  have  been  found  by  Rossi  and  Murri. 

In  the  case  of  Rossi  (followed  by  an  autopsy),  the  cerebellar 
symptoms  are  mentioned.  There  was  intention  tremor  of  the 
arms,  adiadochokinesis  and  asynergy  of  the  legs  (see  page  — ). 
There  was  a  manifest  Romberg.  But  besides  the  cerebellar 
lesion  Rossi  noted  lesions  of  the  posterior  column  and  of  the 
posterior  roots. 

This  very  brief  bird's-eye  view  of  the  pathology  of  the  cere- 
bellum suggests  to  us  the  'following  reflections :  ( i )  Observations 
of  primitive  atrophy  of  the  cerebellum  are  very  rare;  (2)  they 
become  exceptional  if  one  only  takes  account  of  the  observations 
in  which  the  other  parts  of  the  neuraxis  are  absolutely  healthy. 

In  the  more  clear-cut  and  typical  observations,  such  as  the  one 
I  published  with  J.  Dejerine  under  the  name  of  olivo-ponto- 
cerebellar  atrophy,  the  symptomatology  is  confined  to  disturb- 
ances of  motility.  They  are  not  due  to  paralysis  or  sensory  dis- 
turbances ;  this  -is  a  fact  upon  which  I  have  already  insisted.  It 
is  above  all  equilibration  which  appears  to  be  the  most  affected; 
during  walking,  during  the  upright  position,  and  in  all  changes  of 
attitude.  The  gait  does  not  at  all  resemble  the  gait  of  a  normal 
person,  where  the  movements  of  the  arms  and  legs  and  trunk  are 
harmoniously  related  to  one  another;  the  compensatory  move- 
ments necessary  for  the  maintenance  of  equilibrium  during  the 
variations  of  attitude,  are  lacking  or  are  imperfect.  Thus,  when 
a  cerebellar  patient  descends  a  stairway,  his  body  is  thrown  too 
far  backward  and  he  risks  a  backward  fall.  When  he  attempts 
to  stand  upon  one  leg,  the  body  is  carried  either  too  much  towards 
the  side  of  the  leg  that  is  lifted  or  too  much  to  the  other  side. 

A  patient  of  M.  Babinski  afflicted  with  a  pontine  affection  in 
which,  apparently,  the  cerebellar  tracts  participated,  presented 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          117 

still  more  marked  disturbances :  During  walking  the  trunk  did  not 
follow  the  legs.  When  a  foot  was  carried  forward,  the  trunk 
did  not  advance  with  it.  M.  Babinski  classes  this  phenomenon  in 
the  group  of  asynergic  phenomena.  I  have  not  yet  observed  this 
fact  in  the  patients  affected  by  cerebellar  atrophy  whom  I  have 
had  occasion  to  examine. 

There  are,  in  cerebellar  cases,  other  things  than  disturbances 
of  equilibration.  There  is  a  general  disorder  of  motility  which 
appears  in  the  execution  of  every  act  and  movement;  as  well  in 
writing  as  in  speech  (scanning),  and  movements  of  the  eyes 
(nystagmus).  In  their  observations  Royet  and  Collet  mention 
oscillations  of  the  vocal  cords.  The  patient  has  difficulty  in  hold- 
ing a  note.  The  reflexes  are  exaggerated. 

Of  what  nature  are  these  disturbances  of  motility?  They 
have  been  differently  interpreted  according  to  various  authors. 
They  have  been  qualified  as  awkwardness,  tremors,  incoordina- 
tipn,  etc.  In  the  most  typical  observation  which  we  published 
with  J.  Dejerine,  the  patient  became  awkward;  when  she  seized 
a  heavy  object,  or  when  she  moved  it,  her  movements  were  slow 
and  hesitating ;  when  she  tried  to  fill  a  glass  the  hand  which  held 
the  bottle  oscillated  and  poured  the  fluid  on  one  side.  Another 
patient,  the  observation  of  which  is  very  comparable  to  the  pre- 
ceding, had  a  certain  awkwardness  of  the  hands ;  thus,  when  she 
tried  to  take  hold  of  an  object,  a  glass,  for  example,  she  seized  it 
too  suddenly. 

M.  Babinski  has  insisted  equally  upon  the  excessive  move- 
ments of  those  affected  with  cerebellar  lesions.  "  If,  for  exam- 
ple, the  patient  carries  the  point  of  his  index  finger  towards  the 
end  of  the  nose,  which  should  be  the  terminal  point  of  the  finger 
after  having  followed  its  course  in  the  desired  direction,  it  does 
hot  stop  when  it  has  reached  the  object,  but  passes  over  it  and 
violently  strikes  the  jaw."  As  another  example,  he  cites  also  the 
fact :  "  When  the  patient  tries  to  trace  a  line  on  a  sheet  of  paper, 
which  should  be  stopped  at  a  determinate  point  it  is  carried  be- 
yond this  limit."  Up  to  now  M.  Babinski  has  only  observed  this 
phenomenon,  as  have  others  also,  as  one  related  to  disturbances  of 
the  cerebellar  apparatus,  where  there  is  also  an  affection  of  the 
medulla  and  the  pons  and  where  the  lesions  are  not  localized 
exclusively  in  the  cerebellum.  In  all  of  the  autopsies  which  have 


n8 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


been  made,  the  lesions  have  been  too  wide  spread  and  numerous 
to  be  attributed  entirely  to  the  cerebellum. 

Recently,  with  Jumentie,  I  have  had  occasion  to  study  more 
in  detail  these  disturbances  of  motility  in  an  individual  very  com- 
parable by  the  ensemble  of  his  symptoms  with  patients  afflicted 
with  olivo-ponto-cerebellar  atrophy.  In  him  the  lack  of  the  pro- 


62  63 

FIGS.  62  and  63.  Dysmetria  in  an  individual  probably  affected  with 
cerebellar  atrophy.  Exaggeraed  opening  of  the  hand  to  let  go  of  a  glass. 
The  phenomenon  is  more  marked  on  the  left  where  the  other  symptoms 
predominate.  (Andre-Thomas  and  Jumentie,  Revue  Neurologique,  No- 
vember, 1909.) 

portion,  the  dysmetria  noted  by  Luciani  and  other  physiologists 
in  animals  deprived  of  the  cerebellum,  was  very  easily  observable. 
When  he  was  asked  to  place  his  finger  upon  his  nose,  the  move- 
ment was  executed  differently  according  to  whether  it  was  spon- 
taneous, rapid  or  slow. 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          lip 

When  the  movement  was  executed  spontaneously  and  natu- 
rally, it  was  done  in  several  stages — it  was  not  continuous.  There 
was,  so  to  speak,  a  certain  degree  of  intention  tremor.  Also  when 
the  finger  reached  the  nose,  the  hand  was  unstable  and  executed 
alternative  movements  of  supination  and  pronation  before  reach- 
ing a  state  of  repose;  the  tremor,  therefore,  was  both  kinetic  and 
static.  It  will  be  studied  further  on.  If  the  movement  was  made 
slowly  and  carefully,  it  was  practically  executed  correctly,  con- 
tinuously, and  did  not  extend  further  than  it  should  have. 

If  the  movement  were  rapid,  the  finger  passed  over  the  object 
and  touched  the  cheek  at  the  side  of  the  nose;  this  time  it  was 
very  clearly  out  of  proportion,  and  there  was  dysmetria. 

Dysmetria  existed  in  all  movements;  if  he  tried  to  take  hold 
of  a  glass  the  hand  was  opened  too  far  (Figs.  62  and  63). 

If  the  patient  was  lying  down  on  the  back,  and  he  was  asked 
to  place  the  heel  of  one  side  upon  the  knee  of  the  other  side,  the 
heel  was  lifted  too  high  and  passed  by  the  knee,  but  was  then 
replaced  upon  the  knee.  The  patient,  if  he  was  standing  and 
asked  to  raise  his  foot  and  then  to  put  it  down  again,  the  foot  was 
so  replaced  that  the  heel  struck  the  ground,  although  the  patient 
was  held  during  this  test  in  a  manner  to  avoid  any  disturbance 
of  equilibrium. 

Dysmetria  differs  from  peripheral  ataxia  by  two  fundamental 
characteristics:  the  complete  or  almost  complete  orientation 
towards  the  object,  and  the  almost  entire  absence  of  the  influence 
of  sight  upon  the  regulation  of  movement. 

Babinski  has  already  drawn  attention  to  the  disturbances  of 
diadochokinesis.  Diadochokinesis  is  the  ability  to  execute  rap- 
idly successive  volitional  movements.  Adiadochokinesis  (Bruns) 
is  the  loss  of  this  faculty.  A  cerebellar  patient  is  not  able  to 
execute  rapidly  and  regularly  alternative  movements  of  supina- 
tion and  pronation,  or  alternative  movements  of  extension  and 
flexion  of  the  forearm  upon  the  arm,  etc.,  although  the  muscular 
force  is  preserved  and  sensibility  is  intact. 

Adiadochokinesis  has  been  noted  by  various  authors  in  indi- 
viduals afflicted  with  cerebellar  affections  (in  the  majority  of 
cases  they  were  tumors).  It  is  mentioned  by  Italo  Rossi  in  a 
case  of  parenchymatous  atrophy  of  the  cerebellum,  and  for  the 
various  reasons  which  we  have  enumerated  above,  observations 


I2O 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


of  this  order  appear  to  us  to  have  a  great  physiological  importance. 
According  to  Babinski  adiadochokinesis  would  be  the  result 


FIG.  64.  Same  patient  as  in  Figs.  62  and  63.  Gait  of  patient  affected 
probably  with  cerebellar  atrophy.  Enlargement  of  the  base  of  support. 
The  gait  is  slow  and  uncertain.  The  right  arm  follows  the  left  leg,  but 
the  inverse  does  not  take  place. 

of  the  fact  that  each  of  these  successive  movements  is  not  pro- 
portional  (demesure),  and  that  the  time  lost  between  the  two 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          121 

successive  movements  is  not  reduced  to  a  minimum.  There  would 
seem  to  be  some  sort  of  delay  in  the  excito-motor  action.  Ac- 
cording to  my  opinion,  dysmetria  plays  a  considerable  and  even  a 
preponderant  role  in  the  production  of  this  phenomenon.  Upon 
the  patient  to  whom  I  have  previously  alluded  I  have  been  able 
to  demonstrate  the  influence  of  dysmetria  upon  the  difficulty  of 
executing  alternative  movements  of  pronation  and  supination  by 
the  following  test:  When,  after  having  directed  the  two  arms 
forward,  they  having  been  put  previously  in  extension  with  the 
palmar  surface  looking  upwards,  the  patient  turns  them  over,  the 
movements  of  pronation  are  exaggerated  on  the  left,  and  the  left 
thumb  is  lowered  further  than  the  right  one.  A  similar  phe- 
nomenon is  produced  when  the  arm  is  put  back  into  supination 
again,  therefore,  diadochokinesis  is  only  present  on  the  left  side. 
On  the  other  hand,  when  the  patient  has  placed  the  arms  in  flexion 
or  extension  by  a  powerful  contraction  and  he  is  asked  to  let 
them  go,  the  decontraction  is  instantaneous  and  attains  its  maxi- 
mum at  once.  In  the  same  way  with  movements  executed  at 
command  there  is  no  delay  in  the  volitional  incitation.  This  is 
why  adiadochokinesis  seems  to  me  to  be  only  the  consequence  of 
dysmetria. 

At  the  moment  when  the  patient  attempts  to  reverse  the  move- 
ment the  initial  movement  is  prolonged,  and  that  is  tha  reason  of 
the  delay. 

The  tremor  of  cerebellar  patients  is  absent  during  repose.  It 
occurs  in  two  conditions :  during  the  execution  of  voluntary  move- 
ments and  during  the  maintenance  of  an  attitude,  or  rather,  at  the 
beginning  of  either  of  these  conditions. 

When  the  tremor  is  analyzed,  as  I  have  done  in  the  case  of 
the  preceding  patient,  it  is  remarked  that  it  is  more  apparent  at 
the  beginning  of  the  movement.  Instead  of  contracting  in  a  con- 
tinuous or  tonic  fashion,  as  in  the  normal  state,  the  muscles  con- 
tract in  several  stages.  Interrupted  and  exaggerated  shocks  can 
be  seen  under  the  skin  which  recall  to  a  certain  extent  those  which 
are  seen  in  the  crises  of  epilepsy.  The  normal  tonicity  has  given 
place  in  a  way  to  clonicity. 

The  tremor  is  manifested  also  during  the  maintenance  of  an 
attitude.  The  patient  takes,  for  example,  a  glass  in  the  left  hand, 
several  brusque  movements  of  pronation  and  supination  are  pro- 


I  22  THE    FUNCTIONS    OF    THE    CEREBELLUM 

duced  before  immobility  is  attained.  This  fact  is  still  more 
marked  if  the  glass  is  filled  with  water.  In  the  same  way,  when 
the  index  finger  and  the  thumb  are  approached  one  to  another, 
one  can  see  very  clearly  in  the  beginning  clonic  shocks  in  the  first 
interossei  muscles.  The  experiment  may  be  varied  by  having  the 
patient  put  the  thumb  and  little  finger  in  apposition.  The  results 
are  identical.  After  a  certain  time  the  shocks  disappear  and  equi- 
librium is  obtained. 

In  this  patient,  therefore,  the  tremor  is  both  static  and  kinetic. 
The  static  tremor  hardly  exists  except  at  the  beginning  of  an 
attitude. 


FIG.  65.    Writing  of  same  patient. 

The  tremor  may  be  explained  in  various  ways :  ( I )  Either  the 
movement  is  too  brusque  and  disproportioned  and  the  patient  cor- 
rects it  spontaneously  by  the  intervention  of  the  antagonist 
muscles;  or  (2)  there  are  pauses  and  recontractions  in  the  muscles. 

According  to  my  opinion,  the  antagonist  muscles  only  play  a 
small  part  in  the  production  of  this  phenomenon.  Their  contrac- 
tion can  neither  be  perceived  by  the  eye  or  by  palpation ;  and  they 
should  be  perceivable  by  one  means  or  the  other  if  they  are  suffi- 
cient to  arrest  the  movement.  It  appears  more  probable  that  there 
are  stoppages  and  recontractions  of  the  muscles.  In  the  normal 
condition  every  voluntary  movement  presents  itself  as  the  effect 
of  a  continuous  contraction,  a  tonic  contraction.  The  difference 
which  exists  between  a  healthy  subject  and  one  suffering  from  a 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM 


I23 


cerebellar  affection  appears  to  be  due,  in  great  measure,  to  the 
fact  that  the  volitional  incitation  which  starts  the  movement  is 
not  prolonged  in  the  last  case  into  a  tonic  contraction. 

The  movement,  therefore,  is  not  only  dys- 
metric  but  discontinuous  (clonic  or  epilep- 
toid),  and  these  characters  are  found  again 
in  various  physiological  actions.  In  the 
speech,  which  is  often  explosive  and  scan- 
ning ;  in  the  writing,  where  the  characters  are 
irregular,  the  lines  of  unequal  length  and 
unevenly  spaced  and  trembling.  The  in- 
tensity of  the  alterations  in  writing  is 
attributable  to  the  fact  that  the  tremor  is 
more  accentuated  at  the  beginning  of  move- 
ments or  attitudes.  That  is  why  actions 
consisting  of  a  succession  of  short  and  rapid 
movements  are  more  compromised  than 
others. 

Dysmetria  and  discontinuity  of  move- 
ment appear  to  us  to  be,  after  the  disturb- 
ances of  equilibrium,  the  fundamental  char- 
acters of  cerebellar  affections. 

Under  the  name  of  asynergia  Babmski 
has  described  the  loss  of  the  faculty  of  asso- 
ciation of  movements. 

(i)  A  normal  subject  placing  his  foot 
upon  a  chair  bends  the  thigh  upon  the  pelvis 
at  the  same  time  that  he  flexes  the  leg  upon 
the  thigh,  a  cerebellar  patient  first  flexes  the 
thigh  upon  the  pelvis  and  then  the  leg  upon 
the  thigh.  The  two  movements  are  not 
simultaneous;  there  is  a  decomposition  of 
the  movement.  This  first  experiment  does 
not  prove  asynergia  unless  the  patient  is 
seated  or  in  a  stable  position,  otherwise  the 
decomposition  of  the  movement  could  very 
well  be  nothing  but  a  voluntary,  calculated  action,  the  patient  be- 
having in  this  way  because  he  is  afraid  of  falling,  and  many 
ataxies  do  not  act  differentlv. 


124 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


(2)  If  one  asks  a  normal  subject  who  is  standing  upright  to 
bend  his  body  and  his  head  backward,  at  the  same  time  that  he 
executes  this  movement  he  flexes  slightly  the  leg  upon  the  foot 
and  the  thigh  upon  the  leg  in  a  manner  to  avoid  a  fall  backwards. 
In  the.cerebellar  patients  examined  by  Babinski  this  compensating 
movement  of  equilibrium  was  lacking,  and  if  they  were  not  held 
they  fell  backwards. 


FIG.  67.     Same  patient.     Model  above,  copy  below. 

(3)  If  the  patient  is  asked  when  he  is  lying  down  in  the  dorsal 
position  on  a  resisting  plane  to  sit  up,  he  cannot  do  it  in  a  normal 
manner.  The  trunk  is  flexed  a  little  upon  the  pelvis,  but  the 
thighs  are  flexed  more  upon  the  pelvis,  and  it  is  these  that  enable 
him  to  assume  a  sitting  position.  The  results  of  these  experi- 
ments are  not  constant.  They  are  positive  in  certain  patients  and 
negative  in  others. 

The  backward  fall  (in  the  second  experiment)  did  not  occur 
in  several  patients  that  I  examined.  In  some  the  movement  was 
badly  executed  and  accompanied  by  oscillations,  but  the  patient 
did  not  fall.  However,  the  patient  in  whom  Babinski  observed 
this  fact  in  all  its  clearness  was  not  a  pure  cerebellar  case,  as 
various  associated  symptoms  enable  us  to  affirm. 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          125 

Finally,  tKe  third  experiment  requires  a  more  delicate  inter- 
pretation. There  are  normal  subjects  who  cannot  sit  up,  or  sit  up 
with  difficulty  in  these  conditions,  and  in  their  repeated  attempts 
they  sometimes  flex  the  thighs  from  the  pelvis.  It  is  necessary, 
therefore,  that  this  movement  of  flexion  of  the  thighs  should  be 
very  accentuated  to  have  real  significance.  I  have  formerly 
attributed  these  disorders  of  equilibration  in  cerebellar  patients 
to  asynergia  without  so  calling  it.  I  have  remarked  that  during 
walking  the  movements  of  the  arms  do  not  associate  themselves 
with  those  of  the  legs  in  cerebellar  patients  as  they  do  in  normal 
subjects.  When  a  cerebellar  patient  descends  a  stairway  the 
movements  of  projection  of  the  trunk  do  not  associate  with  the 
movements  of  the  legs.  The  first  have  a  retardation  compared 
to  the  second.  In  the  attempts  to  stand  upon  one  leg,  the  body 
is  inclined  too  much  to  the  side,  either  to  the  right  or  to  the  left. 
As  I  have  previously  noted  in  my  thesis,  those  movements 
which  tend  to  displace  the  center  of  gravity  do  not  provoke  the 
tonic  muscular  reactions  which  assure  the  perfect  maintenance 
of  equilibrium.  The  loss  of  these  reactions  of  equilibration  in 
cerebellar  patients  is  only  in  a  certain  way  a  manifestation  of 
asynergia.  Besides,  in  the  experiments  invented  by  M.  Babinski, 
does  not  asynergia  manifest  itself  by  preference  in  those  move- 
ments of  the  whole  in  which  there  is  a  question  of  equilibrium? 

Babinski  has  also  noted  catalepsy  in  one  patient  (this  patient 
was  not  a  pure  cerebellar  type)  ;  that  is  to  say,  a  tendency  to  main- 
tain fixed  attitudes  for  a  longer  time  than  a  normal  subject. 
Without  catalepsy  cerebellar  patients  would  have  the  power  to 
maintain  fixed  attitudes  just  as  long  as  a  normal  subject.  With  a 
patient  lying  upon  the  back,  the  thighs  flexed  upon  his  pelvis,  the 
legs  slightly  flexed  upon  the  thighs,  and  the  feet  separated  from 
one  another  when  the  patient  raises  his  limbs  both  they  and 
the  trunk  are  affected  at  first  by  oscillations  of  large  amplitude, 
and  then  at  the  end  of  some  moments  the  body  and  the  legs  be- 
come fixed. 

I  have  also  noticed  this  phenomenon  in  a  patient  apparently 
afflicted  with  a  cerebellar  affection.  When  the  patient  is  placed 
upon  the  back  (this  is  the  attitude  of  choice  indicated  by  Ba- 
binski) with  the  thighs  flexed  upon  the  pelvis  and  the  legs  slightly 
flexed  upon  the  thighs,  the  body  is  at  first  unstable,  or  oscillates 


126  THE    FUNCTIONS    OF    THE    CEREBELLUM 

around  the  longitudinal  axis.  The  same  thing  happens  in  the 
case  of  the  legs,  which  do  not  at  first  rest  immobile,  then  the  oscil- 
lations disappear  and  the  patient  can  preserve,  for  a  very  long 
time,  the  same  attitude.  Occasionally  one  may  note  some  very 
fine  oscillations.  In  fact  there  does  not  exist  aj:  this  moment  any 
appreciable  difference  between  that  and  what  one  sees  in  the  case 
of  a  normal  subject.  The  stability  is  in  contrast  with  the  oscilla- 
tions which  were  produced  at  the  beginning  of  the  attitude.  This 
is  exactly  what  takes  place  in  static  tremor.  What  is  true  for 
the  stability  of  partial  movements  is  also  so  for  the  movements  of 
equilibration.  Cerebellar  patients  have  a  special  difficulty  in 
establishing  stability  or  equilibrium  promptly. 

The  movements  of  cerebellar  patients  are  usually  slow,  but 
this  slowness  is  not  the  immediate  consequence  of  the  functional 
insufficiency  of  the  cerebellum,  because  they  are  able  to  execute 
rapid  movements.  The  slowness  is  (apparently)  willed,  inten- 
tional, and  has  for  its  object  the  purpose  of  overseeing  the  move- 
ments and  of  combating  more  efficiently  the  tremor  and  the 
dysmetria. 

Patients  afflicted  with  cerebellar  atrophy  resist,  generally  suffi- 
ciently well,  pushings  and  pullings  which  may  be  exercised  upon 
them  for  the.  object  of  making  them  lose  their  equilibrium.  I 
have  never  observed  in  them,  or  at  any  rate,  to  the  same  degree,  a 
provoked  latero-,  antero-  or  retro-pulsion,  so  often  seen  in  patients 
afflicted  with  Parkinson's  disease. 

In  those  patients  whom  I  have  examined  on  a  turn-table 
in  order  to  study  their  reactions  to  centrifuging,  I  have  not  been 
able  to  notice  any  appreciable  difference  between  them  and  normal 
subjects. 

IV.   LESIONS  OF  THE  CEREBELLAR  PEDUNCLES  IN  MAN 

The  experiments  made  upon  animals  and  the  observations  col- 
lecte.d  concerning  the  systemic  or  non-systemic  lesions  of  the  cere- 
bellar paths,  whether  medullary  or  spinal,  in  man  are  comparable. 
Among  these  observations  are  some  cases  described  under  the 
name  of  heredito-cerebellar  ataxia  and  of  which  the  principal 
lesions  are  represented  by  the  systemic  degeneration  of  the  direct 
cerebellar  tracts  and  the  tract  of  Cowers  (Andre-Thomas  and 
J.-Ch.  Roux).  The  posterior  columns  are  degenerated  to  a  lesser 


SYMPTOMATOLOGY    OF    AFFECTIONS    OF    CEREBELLUM          1 2/ 

degree,  so  that  the  disease  assumes  the  clinical  form  very  com- 
parable to  cerebellar  affections  (slowness  of  movements,  tremors, 
oscillating  gait,  wavering,  dynamic  nystagmus).  It  borrows  also 
some  of  its  symptoms  from  Duchenne's  disease  (sign  of  Rom- 
berg,  pains  and  disturbances  of  sensibility,  etc.). 


68  69 

FIGS.  68  and  69.  The  various  attitudes  of  the  cerebellar  gait,  after 
enlargements  from  instantaneous  photographs,  in  a  woman  affected  with  a 
focus  of  softening  at  the  level  of  the  left  restiform  body,  and  with  two 
small  foci  of  multiple  sclerosis  situated  the  one  to  the  left  in  the  central 
bundle  of  the  tegmentum,  the  other  to  the  right  at  the  superior  extremity 
of  the  facial  nucleus  behind  the  superior  olive.  These  lesions  are  repre- 
sented in  Figs.  72  and  73.  Disturbances  of  equilibrium,  enlargement  of  the 
base  of  support,  uncertainty  of  gait,  abduction  of  the  arms,  particularly 
of  the  left  one.  (Andre-Thomas,  Revue  Neurologique,  January,  1905.) 

Certain  medullary  lesions  give  rise  to  symptoms  which  recall 
the  unilateral  and  bilateral  destructions  of  the  cerebellum.  Ba- 
binski  and  Nageotte  observed  a  patient  who  presented  hemi- 


128  THE    FUNCTIONS    OF    THE    CEREBELLUM 

asynergia  of  the  left  leg,  latero-pulsion  towards  the  Ijeft  and  a 
slight  tremor  of  the  arms.  (There  existed  also  a  slight  hemi- 
plegia  with  right  hemi-ansesthesia,  difficulty  of  swallowing,  and  a 
slight  contraction  of  the  left  pupil.)  A  histological  examination 


70  71 

FIGS.  70  and  71.  The  various  attitudes  of  the  cerebellar  gait,  after 
enlargements  from  instantaneous  photographs,  in  a  woman  affected  with  a 
focus  of  softening  at  the  level  of  the  left  restiform  body,  and  with  two 
small  foci  of  multiple  sclerosis  situated  the  one  to  the  left  in  the  central 
bundle  of  the  tegmentum,  the  other  to  the  right  'at  the  superior  extremity 
of  the  facial  nucleus  behfnd  the  superior  olive.  These  lesions  are  repre- 
sented in  Figs.  72  and  73.  Disturbances  of  equilibrium,  enlargement  of  the 
base  of  support,  uncertainty  of  gait,  abduction  of  the  arms,  particularly 
of  the  left  one.  (Andre-Thomas,  Revue  Neurologique,  January,  1905.) 

of  a  series  of  sections  showed  the  presence  of  multiple  softenings 
in  the  left  half  of  the  medulla  and  the  fibers  of  the  restiform  body 
had  been  partially  divided.  An  analogous  symptomatology  is  en- 
countered in  cases  of  tumor  of  the  cerebello-pontine  angle,  that 


I29 

is  to  say,  those  which  are  developed  in  the  angle  formed  by  the 
pons  and  the  cerebellum.  These  are  very  complex  cases:  firstly, 
because  it  is  a  question  of  tumors  which  compress  at  the  same 
time  the  cerebellum,  the  middle  cerebellar  peduncle  and  the  pons, 


FIGS.  72  and  73.     Lesions  of  the  medulla  giving  occasion  to  the  disturb- 
ances of  gait  represented  in  Figs.  68  to  71. 

and  also  because  the  vestibular  nerve  is  usually  likewise  affected. 
Consequently  the  coexistence  of  functional  disturbances  of  the 
vestibular  nerve  or  its  central  paths  contributes  towards  augment- 
ing considerably  the  disturbances  of  equilibrium  present.  In 


I3O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

a  case  of  softening  of  the  medulla  oblongata,  located  at  the  union 
of  the  inferior  third  with  the  superior  two  thirds  of  the  left  half 
in  the  lateral  reticulated  substance  (encroaching  upon  the  inferior 
extremity  of  the  restiform  body),  and  associated  with  a  patch 
of  sclerosis  upon  the  pathway  of  the  central  bundle  of  the  teg- 
mentum,  I  have  observed  disturbances  of  motility  comparable  to 
those  of  the  cerebellum.  The  attitudes  represented  in  Figs.  68 
to  71,  which  are  enlargements  from  photographic  plates,  give 
better  than  any  description  an  idea  of  the  intensity  of  the  disturb- 
ances of  equilibrium.  Perhaps  in  this  case  there  is  occasion  to 
take  into  consideration  the  interruption  of  other  fibers  than  cere- 
bellar  fibers,  particularly  those  of  the  descending  root  of  the 
eighth  pair  (vestibular  fibers).  The  same  consideration  is  appli- 
cable to  the  experimental  section  of  the  restiform  body  which 
compromises  almost  always  the  anatomical  and  physiological  con- 
tinuity of  the  same  root. 

Lesions  of  the  tegmentum  often  give  rise  to  a  permanent  or 
intention  tremor  of  the  limbs  on  the  side  opposite  the  lesion. 
This  tremor  is  very  similar  in  certain  cases  to  the  intention  tremor 
of  multiple  sclerosis  (an  affection  in  which  the  superior  cerebellar 
peduncles  are  frequently  the  seat  of  pathological  foci).  It  is  a 
part  of  the  syndrome  of  Benedikt,  which  consists  of  a  paralysis 
more  or  less  complete  of  the  third  pair,  with  a  slight  crossed 
hemiplegia,  associated  with  tremor,  and  which  is  due  to  a  lesion 
of  the  tegmentum  involving  to  a  variable  degree  at  the  same  time 
with  the  root,  or  the  nucleus,  of  the  third  pair,  the  superior  cere- 
bellar peduncle  or  the  region  of  the  red  nucleus.  Lesions  also  of 
the  cerebellar  olive,  or  of  the  superior  cerebellar  peduncle,  have 
been  noted,  which  have  caused  disturbances  of  motion,  recalling  at 
the  same  time  chorea  and  the  intention  tremor  of  multiple 
sclerosis. 

All  these  facts  are  allied  to  the  intention  tremor  observed  by 
Ferrier  and  Turner  in  the  monkeys  in  which  they  divided  the 
superior  cerebellar  peduncle. 


PART  SECOND 

INTERPRETATION 

After  having  set  forth  the  results  of  experimental  physiology 
and  clinical  observation,  it  is  well  to  pass  in  review  the  various 
interpretations  of  the  several  authors  to  explain  the  mechanisms, 
that  is  to  say,  the  divers  theories  propounded  as  to  the  functions 
of  the  cerebellum.  The  theories  of  a  purely  hypothetical  nature 
will  only  be  mentioned.  Only  those  should  be  retained  and  dis- 
cussed which  are  based  upon  the  findings  of  clinical  and  experi- 
mental physiological  observation.  I  will  afterwards  endeavor  to 
make  an  impatrial  criticism,  appealing  only  to  positive  facts,  and 
reducing  to  a  minimum  the  role  of  hypothesis,  which,  in  spite  of 
everything,  is  inevitable  in  a  question  of  a  purely  doctrinal  order. 


CHAPTER  VI 
THE   CEREBELLUM   AND    THE   ORGANIC   FUNCTIONS 

One  might  expect  that  the  discussion  would  be  limited  to  a 
very  restricted  series  of  facts  and  would  not  have  reference  to 
anything  except  the  mechanisms  of  the  recorded  phenomena. 
However,  there  is  far  from  being  an  unanimous  accord  as  to  the 
facts  themselves,  and  if  one  takes  into  consideration  all  of  the 
theories  that  have  been  propounded,  one  can  say  that  there  is  no 
function  of  animal  life,  or  of  the  life  of  relation,  into  which  the 
cerebellum  does  not  intrude. 

Willis  has  maintained  that  the  cerebellum  is  not  foreign  to  the 
organic  functions  and  to  the  involuntary  movements,  meaning  by 
these  last  expressions  not  only  automatic  or  reflex  movements,  but 
those  of  animal  life,  the  beatings  of  the  heart,  respiration,  di- 
gestion, etc.,  etc.  The  intervention  of  the  cerebellum  in  the 
glandular  and  visceral  functions  has  been  accepted  by  some  great 
physiologists,  who  bring  to  bear  the  results  of  various  experi- 
ments. Claude  Bernard  stated  that  he  stopped  the  secretion  of 
the  crop  in  pigeons  by  wounding  the  cerebellum,  that  the  excita- 
tion of  the  cerebellum  would  produce  movements  in  the  bladder, 
in  the  stomach,  and  in  the  intestinal  canal.  According  to  Duges, 
its  intimate  relations  with  the  pneumogastric  nerve  cause  it  to 
intervene  in  respiration  and  digestion,  in  the  complex  instinctive 
phenomena,  in  acts  relative  to  the  sustaining  of  life,  in  the  appe- 
tites, and  in  the  necessity  of  breathing. 

Likewise,  according  to  different  authors,  the  sexual  instinct 
and  the  genital  functions  are  located  in  the  cerebellum.  Goll  was 
the  principal  protagonist  of  this  theory.  He  made  the  cerebellum 
the  organ  of  the  instinct  of  propagation  or  of  the  inclination  to 
physical  love.  To  the  support  of  this  hypothesis  he  invoked  the 
following  arguments :  Persons  of  a  very  ardent  temperament  feel 
a  tension  and  a  sensation  of  heat  in  the  back  of  the  neck,  particu- 
larly after  excessive  and  profuse  emissions  or  after  prolonged 
continence.  In  rabbits  deprived  of  a  testicle  the  lobe  of  the  cere- 

132 


THE    CEREBELLUM    AND    THE    ORGANIC    FUNCTIONS  133 

bellum  on  the  opposite  side  from  the  removed  testicle  is  smaller 
and  the  corresponding  occipital  boss  is  more  flattened  than  the 
other.  Females  have  a  cerebellum  smaller  than  males  because  the 
sentiment  of  physical  love  is  less  pronounced  in  them,  and  finally, 
the  complete  development  of  the  cerebellum  coincides  with  that 
of  physical  love.  All  of  these  propositions  are  in  disaccord  with 
reality ;  there  is  no  appreciable  difference  in  the  cerebellum  of  males 
and  of  females.  The  development  of  the  cerebellum  is  completed 
a  long  time  before  the  appearance  of  the  genital  instinct.  Castra- 
tion does  not  in  any  way  involve  the  atrophy  of  the  cerebellum 
(Leuret  and  Lelut). 

It  is  known  what  the  physiological  works  of  Goll  were  worth. 
He  had,  however,  his  partisans,  and  his  ideas  seem  to  be  con- 
firmed by  some  physiologists  of  talent.  Budge  and  Valentin  are 
said  to  have  provoked,  by  the  direct  stimulation  of  the  cerebellum, 
movements  in  the  vesiculse  seminales,  the  testicles,  the  Fallopian 
tubes  and  in  the  uterus.  Spiegelberg  obtained  uterine  contrac- 
tions by  mechanical  or  chemical  irritation  of  some  one  or  other 
region  of  the  cerebellum;  the  vesicular  turgescence,  the  cause  of 
erection,  could  be  produced  according  to  Ekhard  by  an  irritation 
of  the  pons.  Thion  reports  the  autopsy  of  a  cow  which  had  a 
calf  without  lactic  secretions  having  been  produced,  and  which 
later  would  not  allow  the  approaches  of  the  male,  and  in  which 
he  found  a  number  of  tubercles  in  the  cerebellum.  Serres  has 
reported  seven  observations  of  apoplexy  of  the  median  lobe,  in 
which  there  was  priapism  and  exaltation  of  the  feeling  of  physical 
love,  and  he  concludes  from  this  that  the  vermis  is  the  excitor  of 
the  organs  of  generation. 

All  of  these  facts  have  only  the  value  of  simple  coincidences 
and  have  not  been  established  with  the  control  and  scientific  rigor 
necessary;  besides,  they  may  be  opposed  by  contradictory  facts 
of  which  the  conclusions  are  more  significant.  Flourens  maintains 
that  the  cerebellum  does  not  intervene  in  any  way  in  the  instinct 
of  propagation  or  of  physical  love,  and  he  bases  this  upon  the 
following  fact:  A  cock  from  which  he  had  removed  the  greater 
part  of  the  cerebellum  attempted  to  mount  the  hens,  but  he  was 
not  able  to  do  so  on  account  of  his  disequilibration,  and  this  great 
physiologist  adds  "  his  testicles  were  enormous."  Since  then  the 
majority  of  physiologists  have  observed  that  the  destruction  of 


134  THE    FUNCTIONS    OF    THE    CEREBELLUM 

the  cerebellum  does  not  interfere  in  any  way  with  the  manifesta- 
tions of  the  sexual  instinct  except  by  the  difficulties  that  are  intro- 
duced towards  the  maintenance  of  equilibrium  or  of  attitudes. 

The  animals  operated  upon  by  Luciani  had  polyuria,  glyco- 
suria  and  acetonuria.  This  Florentine  physiologist  attributed 
these  phenomena  to  action  upon  the  neighboring  fourth  ventricle. 
In  the  same  way  emaciation,  alopecia  and  the  various  dystrophic 
disturbances  are  not  attributable  directly  to  the  lack  of  cerebellar 
innervation;  they  are  indirect  and  inconstant  effects. 

INFLUENCE  OF  THE  CEREBELLUM  ON  DEVELOPMENT  AND  GROWTH 

The  cerebellum  does  not  appear  to  have  any  influence  upon  the 
development  of  the  body  and  upon  growth.  In  the  cases  of  de- 
struction of  one  half  of  the  cerebellum  in  young  dogs  aged  from 
fifteen  days  to  three  weeks,  I  was  not  able  to  observe  any  differ- 
ence between  the  two  sides  of  the  body.  Certainly  when  these 
animals  are  compared  to  other  dogs  of  the  same  litter  it  is  observed 
that  their  growth  is  less  rapid  (Borgherindi  and  Gallerini,  and 
Andre-Thomas).  The  operative  shock  and  traumatism  are  seem- 
ingly the  principal  cause  of  this.  However,  Russell  observed  a 
cat  in  which  the  right  lobe  was  only  about  half  the  size  of  the  left 
lobe.  This  atrophy  was  manifested  during  life  by  an  accentuated 
paresis  of  the  two  extremities  of  the  right  side,  and  the  right  paw 
was  a  little  shorter  than  the  left.  But  was  this  partial  agenesis 
of  the  cerebellum  really  the  cause  of  the  retardation  of  the  growth 
of  the  corresponding  limb?  One  can  well  doubt  it,  since,  in  the 
various  observations  of  agenesis  of  the  lateral  lobe  in  man,  no 
similar  asymmetry  has  been  mentioned. 


CHAPTER  VII 
THE    CEREBELLUM    AND    SENSIBILITY 

The  relations  of  the  cerebellum  to  sensibility  have  been  vari- 
ously estimated.  Admitting  such  relations  some  authors  base 
their  conclusions  upon  anatomical  facts,  some  upon  the  results  of 
physiological  experiments,  and  others  upon  clinical  observation. 

In  the  domain  of  sensibility  there  are  generally  distinguished 
general  sensibility  and  the  special  sensibilities  (hearing,  sight, 
smell  and  taste).  The  relations  of  the  cerebellum  to  sensibility 
should  be  studied  from  this  double  point  of  view. 

THE  CEREBELLUM  AND  GENERAL  SENSIBILITY 

Lapeyronie  and  Pourfour.  du  Petit  base  their  conclusions  upon 
clinical  observations ;  Saucerotte,  Foville  and  Pinel-Grandchamp 
on  the  results  of  their  physiological  experiments,  and  conclude 
that  the  cerebellum  is  an  organ  eminently  fitted  to  the  sensory 
function. 

Foville  and  Pinel-Grandchamp  even  recognize  a  sensibility 
peculiar  to  the  cerebellum.  Duges,  considering  that  the  cerebel- 
lum receives  in  its  hemispheres  the  sub-spinal  bundles  of  the 
spinal  cord,  looks  at  the  cerebellum  as  an  organ  belonging  to  gen- 
eral sensibility;  it  would  preside  also  over  taste  and  hearing, 
owing  to  its  relations  with  the  glosso-pharyngeal,  tri facial  and 
auditory  nerves. 

The  deep  sensibilities  and  the  muscular  sense  will  be  consid- 
ered later  on.  Only  the  sensibilities  to  contact  and  pain  will  be 
considered  here.  According  to  Luciani,  sensibility  to  contact  is 
respected.  He  has  noted  that  if  one  touches  the  animal  while  he 
eats,  or  while  he  has  his  eyes  bandaged,  he  reacts  by  a  movement 
which  indicates  that  he  has  felt.  Russell  maintains,  on  the  con- 
trary, that  the  destruction  of  one  half  of  the  cerebellum  is  fol- 
lowed by  an  anesthesia  and  an  analgesia  of  the  same  distribution 
as  the  motor  paresis,  that  is,  localized  in  the  two  limbs  on  the 
side  of  the  lesion  and  the  posterior  limb  of  the  other  side;  the 


136  THE    FUNCTIONS    OF    THE    CEREBELLUM 

total  destruction  of  the  cerebellum  entails  an  anesthesia  and  an 
analgesia  of  all  four  limbs. 

Regarding  sensibility,  however,  clinical  observations  appear 
to  me  to  have  more  value  than  physiological  experiments.  In  an 
animal,  sensibility  is  always  difficult  of  exploration  and  one  can- 
not judge  as  to  its  conservation  or  alteration  except  by  reflex 
acts.  Atrophies  of  the  cerebellum  exclusively  cortical  or  gener- 
alized do  not  give  rise  in  man  to  any  disturbance  of  sensibility, 
either  superficial  or  profound. 

Besides,  the  proximity  of  the  nuclei  of  the  posterior  columns 
and  of  the  cerebellum  allow  one  to  suspect  that  they  have  been 
compressed  by  blood  clots  following  the  experimental  destruc- 
tions. It  is  perhaps  through  this  mechanism  that  one  must  ex- 
plain the  sensory  disturbances  noted  by  various  authors ;  besides, 
they  are  transitory  and  only  last  a  few  days  (Russell). 


Among  the  special  sensibilities  hearing  is  the  one  which  one 
most  willingly  localizes  in  the  cerebellum.  Treviranus  has  already 
established  a  relation  between  the  degree  of  development  of  the 
organ  of  hearing  and  that  of  the  cerebellar  hemispheres  on  one 
side  and  between  the  vermis  and  the  trifacial  on  the  other  side. 
The  macroscopic  relations  between  the  eighth  pair  and  the  bulbo- 
pontine  angle  are  of  a  nature  to  justify  this  hypothesis.  Today 
it  is  known  how  little  faith  we  must  put  in  the  findings  of  topo- 
graphical anatomy.  One  can  only  obtain  a  knowledge  of  the  rela- 
tions between  the  different  parts  of  the  neuraxis  based  upon  sec- 
ondary degenerations  in  man  and  animals. 

The  eighth  pair  is  formed  from  two  roots.  One  takes  its 
origin  in  the  cochlea,  that  is,  the  cochlear  or  auditory  root.  The 
other,  which  originates  in  the  semicircular  canals  of  the  vestibule 
and  saccule,  is  the  vestibular  root,  or  the  vestibular  nerve.  The 
cochlear  root  serves  exclusively  for  the  transmission  of  sound 
waves  and  terminates  in  the  ponto-medullary  nuclei,  the  ventral 
auditory  ganglion  and  the  acoustic  tubercle,  and  does  not  contract 
any  relation,  direct  or  indirect,  with  the  cerebellum.  The  ves- 
tibular root  is  of  more  interest  to  us :  First,  because  some  of  its 
fibers,  at  least  in  animals,  terminate  in  the  nucleus  of  the  tegmen- 
tum,  second,  because  almost  all  of  its  fibers  arborize  around  the 


THE    CEREBELLUM    AND    SENSIBILITY  137 

cells  of  three  nuclei  (nucleus  of  Deiters,  nucleus  of  Bechterew,  and 
the  triangular  auditory  nucleus),  which  are  themselves  in  intimate 
relations  with  the  cerebellum.  The  study  of  a  microscopic  series 
of  sections  of  the  medulla,  the  pons,  and  the  cerebellum,  show,  in 
effect,  that  there  exists  between  these  nuclei  and  the  central  nuclei 
of  the  cerebellum,  an  important  anatomical  connection,  repre- 
sented by  the  internal  and  external  semicircular  fibers.  Secon- 
dary degenerations  show  besides,  that  after  destructions  of  the 
vermis,  lesions  of  the  vermis  and  of  a  hemisphere,  the  degenerated 
fibers  can  be  followed  to  the  nuclei  of  the  vestibular  nerve;  on 
the  other  hand  one  cannot  affirm  that  any  fibers  which  go  to  the 
cerebellum  come  from  these  nuclei. 

One  cannot,  therefore,  affirm  that  the  cerebellum  is  a  center 
for  the  storage  of  peripheral  excitations  gathered  by  the  vestibu- 
lar nerve,  and,  consequently,  a  center  of  perception  for  this  class 
of  impressions. 

The  most  that  one  can  say,  based  upon  the  existence  of  some 
vestibular  fibers  which  go  directly  to  the  nucleus  of  the  roof,  is  to 
admit  with  Stefani  that  the  cerebellum  utilizes  impressions  which 
are  furnished  by  the  terminations  of  the  nerves  of  the  eighth  pair 
to  regulate  the  attitude  of  the  head  in  space. 

The  fact  that  in  cerebellar  patients  there  is  no  disturbance  of 
the  compensatory  reactions  of  the  head  and  eyes,  nor  of  the  per- 
ceptions of  movements  of  rotation  on  the  centrifugal  apparatus, 
may  be  cited  still  further  against  the  opinion  of  those  authors  who 
make  of  the  cerebellum  a  center  of  perception  of  vestibular  im- 
pressions. Spontaneous  vertigo  does  not  enter  either  into  the 
symptomatic  picture  of  cerebellar  atrophies,  at  any  rate,  if  it  is 
not  foreign  to  certain  phenomena  produced  by  experimental 
lesions  of  the  cerebellum  (Vulpian  and  deCyon),  it  does  not  play 
any  except  a  very  minor  role  in  the  pathological  physiology  of  the 
disorders  of  equilibration. 

But  one  must  admit  that  the  cerebellum  exercises  some  action 
upon  the  medullary  nuclei  of  the  vestibular  nerve.  Since  these 
nuclei,  the  nucleus  of  Deiters  and  the  nucleus  of  Bechterew,  con- 
tain cells  the  axis  cylinders  of  which,  after  a  more  or  less  com- 
plicated course,  terminate  in  the  nuclei  of  the  third  and  the  sixth 
pairs,  and  in  the  gray  substance  of  the  anterior  horn,  they  repre- 
sent important  reflex  centers. 


138  THE    FUNCTIONS    OF    THE    CEREBELLUM 

The  posterior  longitudinal  fasciculus  is  the  principal  path  fol- 
lowed by  these  fibers.  The  relations  of  each  nucleus  of  Deiters- 
Bechterew  are  principally  crossed  for  the  third  pair  and  direct 
for  the  spinal  column. 

It  is  established,  on  the  other  hand,  that  the  cerebellar  fibers 
which  terminate  in  the  nuclei  of  the  vestibular  nerve  are  derived 
from  the  central  nuclei  (principally  the  nucleus  of  the  tegmentum), 
and  as  these  last  named  nuclei  receive  in  their  turn  fibers  of  pro- 
jection from  the  cortex  (and  more  particularly  from  the  region 
of  the  vermis),  it  results  that  the  vermis  is  the  territory  of  the 
cerebellar  cortex,  of  which  the  functional  activity  is  the  most 
intimately  connected  with  that  of  the  nuclei  of  the  vestibular 
nerve. 

I  will  discuss  later  the  importance  of  these  anatomical  rela- 
tions in  connection  with  the  various  hypotheses  which  have  been 
given  out  on  the  physiology  of  the  cerebellum. 

The  cerebellum  does  not  play  any  role  in  the  perception  of 
visual,  gustatory,  or  auditory  sensations. 


CHAPTER  VIII 
THE  CEREBELLUM   AND   INTELLIGENCE 

It  is  apparent  that  in  order  to  study  the  role  of  the  cerebellum 
in  the  elaboration  of  psychic  processes,  it  is  necessary  for  one 
to  address  oneself  to  the  highest  individual  from  the  intellectual 
point  of  view  in  the  animal  series,  that  is,  to  man.  The  anatomo- 
clinical  method  shows  itself  here  superior  to  the  method  of  experi- 
mental physiology. 

While  it  is  true  that  in  a  sufficiently  large  number  of  observa- 
tions the  coincidence  of  intellectual  disturbances  with  cerebellar 
lesions  has  been  noted,  how  many  times  has  a  relation  of  cause 
and  effect  been  established  in  a  rigorously  scientific  manner  be- 
tween the  two?  Those  who  have  thought  that  they  have  found 
this  relation  have  not  taken  into  consideration  the  possibility  of 
the  coexistence  of  cerebral  lesions,  or  the  insufficiency  of  the 
examination  of  the  cerebrum.  Courmont,  who  has  consecrated 
a  large  volume  to  the  study  of  the  functions  of  the  cerebellum, 
has  not  been  able  to  avoid  this  objection.  He  has  utilized  for  the 
support  of  his  doctrine — for  him  the  cerebellum  is  the  organ  of 
psychic  sensibility — observations  in  which  there  existed  at  the 
same  time  cerebellar  and  cerebral  lesions. 

With  this  preconceived  idea  as  a  point  of  departure,  he  chose 
the  rat  as  the  subject  of  his  experiments,  because,  said  he,  "  it  is 
very  impressionable."  In  the  rat  deprived  of  the  cerebellum  he 
examined  the  modifications  of  the  five  modes  of  expression  of 
the  emotions  of  the  animal:  "The  attitude,  the  gesture,  the  jump, 
the  flight,  and  the  cry."  After  the  operation,  the  animal  assumed 
an  indifferent  attitude ;  he  did  not  spring  away ;  at  each  noise 
which  startled  him  the  jump  was  not  the  same.  "  There  was  no 
more  any  modality,  there  was  a  simple  reflex  movement;  there 
was  no  tendency  to  flight,  or  if  there  was,  it  was  slow  and  apa- 
thetic ;  the  psychic  cry  did  not  exist."  Among  these  disturbances 
some  may  be  explained  by  disorders  of  motility,  others  by  the 
traumatism,  or  the  shock  of  the  operation,  and  there  is  nothing 


I4O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

to  prove  that  they  were  the  consequence  of  any  psychic  disorder. 

According  to  Luciani  monkeys  appear  to  have  their  natural 
timidity  exaggerated;  in  dogs,  during  the  first  few  days  that 
follow  the  operation,  there  seems  to  be  an  increase  of  their  affec- 
tionateness.  Later  they  are  lazier  and  more  apathetic.  In  this 
there  is  nothing  that  indicates  a  serious  perturbation  or  suppres- 
sion of  psychic  sensibility. 

Patients  afflicted  with  cerebellar  atrophy  are  usually  slow  in 
their  acts  and  in  their  reactions,  and  that  is  easily  explained  by 
the  disturbances  of  motility  and  of  locomotion.  The  apparent 
asthenia  is  caused  seemingly  simply  by  the  suppression  of  an 
organ,  which  permits,  in  a  sort  of  reflex  manner,  the  play  of  all 
the  mechanisms  adapted  to  the  perfect  execution  of  movement, 
and  which  permits  the  cerebral  activity  to  dispose  itself  almost 
entirely  in  the  elaboration  of  psychic  processes.  As  one  will  see 
further  on  the  cerebrum  supplies,  in  a  large  measure,  the  insuffi- 
ciency or  the  absence  of  the  cerebellum.  If  a  man  is  obliged  to 
exercise  his  will  and  to  constantly  oversee  his  equilibrium,  his 
attention  would  be  distracted  from  phenomena  purely  psychic, 
and  this  would  be  at  the  expense  of  the  development  and  the 
upkeep  of  his  intelligence. 


CHAPTER  IX 
THE  CEREBELLUM  AND  MOTILITY 

The  most  striking  phenomena  observed  in  animals  where  the 
cerebellum  has  been  totally  or  partially  destroyed,  and  in  man 
affected  with  cerebellar  lesions,  are  above  all  disturbances  of 
motility.  This  is  the  almost  unanimous  opinion  both  of  physiolo- 
gists and  clinicians.  The  same  unanimity  is  lacking  when  it  is  a 
question  of  interpreting  them.  For  some  the  cerebellum  is  a 
center  of  energy,  or  reinforcement  of  muscular  tonus;  for  others 
a  center  of  coordination,  and  for  still  others  its  role  is  much  more 
limited,  it  is  a  center  of  equilibration.  As  a  center  of  coordina- 
tion its  role  has  been  variously  interpreted.  For  some  authors 
it  is  intimately  connected  with  the  perception  of  deep  sensation 
and  therefore  the  center  of  muscular  sense;  the  majority,  how- 
ever, consider  that  it  does  not  contribute  in  any  way  towards  the 
perception  of  sensations.  This  hypothesis  will  be  discussed  first, 
as  it  is  of  fundamental  importance  to  know  whether  or  not  the 
cerebellum  is  a  center  of  perception  and  of  sensory  impressions. 

THE  CEREBELLUM  AND  THE  MUSCULAR  SENSE 

Magendie  had  already  considered  the  cerebellum  as  the  center 
of  muscular  sense.  Lussana  and  Lewandowsky  are  the  principal 
protagonists  of  this  theory. 

According  to  Lussana  the  cerebellum  is  the  central  organ  of 
the  muscular  sense,  and  he  considers  the  posterior  columns  as  the 
organs  of  transmission  (this  is  an  error,  since  the  contingent  of 
fibers  of  the  posterior  columns  which  terminate  in  the  cerebellum 
is  extremely  small;  several  anatomists  even  deny  their  existence). 
According  to  this  author  the  coordinating  innervations  from 
the  two  sides  of  the  body  unify  and  lose  themselves  in  the 
cerebellum,  and  it  is  from  this  resultant  that  is  deduced  the  appre- 
ciation of  the  center  of  gravity  of  the  body  and  its  various  parts 
in  their  movements  so  complex  and  their  functions  so  varied. 
The  fibers  of  the  spinal  cord  which  terminate  in  the  cerebellum 

141 


142  THE    FUNCTIONS    OF    THE    CEREBELLUM 

bring  to  it  the  notions  of  space,  of  touch,  and  of  pressure.  It 
coordinates  in  this  manner  voluntary  movements  adapted  to  trans- 
lation of  the  body,  in  the  same  way  that  a  coordination  of  lan- 
guage and  the  movements  of  the  face  are  made  in  the  olives,  and 
the  movements  of  mastication  and  of  the  mouth  are  made  in  the 
medulla  oblongata.  The  cerebellum  contains  also  the  centers  for 
the  coordinating  movements  of  the  eyes.  The  ataxia  strikes  in 
animals  the  thoracic  limb  because  in  animals  the  center  of  gravity 
is  nearer  the  thorax;  for  the  same  reason  it  predominates  in  the 
lower  limbs  in  man. 

The  works  of  Lussana  have  contributed  to  throw  light  upon 
the  functions  of  the  cerebellum  in  their  relations  to  equilibration 
and  the  coordination  of  movements,  but  he  has  shown  no  experi- 
ment which  was  of  a  nature  to  prove  that  the  cerebellum  is  a 
center  of  perception  of  muscular  sensations  and  of  deep  sensations 
in  general.  Besides,  it  is  only  in  man  that  it  is  possible  to  study 
this  type  of  perception,  as  it  is  with  every  form  of  conscious 
sensation. 

The  theory  of  Lussana  has  been  taken  up  again  recently  by 
Lewandowsky.  He  invokes  to  the  support  of  his  thesis  some 
phenomena  which  do  not  lack  interest. 

According  to  Lewandowsky  "  each  motor  disturbance  follow- 
ing a  cerebellar  lesion  is  accompanied  by  disturbances  of  the  mus- 
cular sense."  To  the  support  of  this  theory  he  cites  certain 
abnormal  attitudes  and  certain  disturbances  of  locomotion.  Among 
the  attitudes  he  insists  upon  that  of  the  fore  paw  during  repose 
(on  the  same  side  as  the  lesion,  if  the  lesion  be  unilateral),  often 
it  does  not  lie  upon  the  plantar  but  upon  the  dorsal  surface.  In 
the  same  way  if  the  animal  is  lying  down  in  the  abdominal  decubi- 
tus  upon  a  table,  and  if  the  paw  (on  the  side  of  the  lesion)  hangs 
over  the  table,  the  animal  does  not  draw  it  back,  whereas  a  healthy 
animal  always  does.  The  hindquarters  may  be  hung  over  the 
edge  of  the  table  and  the  animal  does  not  make  any  effort  to  draw 
them  upon  the  table. 

The  motility  of  the  isolated  movements  of  the  limbs  is  also 
disturbed.  For  instance,  a  dog  wishes  to  seize  a  bone  with  its 
paw,  very  often  the  paw  passes  over  it.  The  majority  of  physiol- 
ogists have  noted  that  during  walking  the  paws  of  the  dog  are 
lifted  too  high.  Lewandowsky  has  noted  the  same  fact  in  other 


THE    CEREBELLUM    AND    MOTTLITY  143 

animals.  In  some  other  animals,  on  the  contrary,  the  paws  are  not 
lifted  high  enough ;  in  the  first  case  he  compares  the  gait  with 
that  of  a  cock,  in  the  second  with  that  of  a  cat.  Not  only  is  the 
amplitude  of  the  movement  exaggerated,  but  it  is  also  too  rapid. 
When  the  dog  reeducates  itself  and  commences  to  walk,  the  mem- 
bers of  the  side  operated  upon  are  lifted  and  replaced  too  sud- 
denly ;  the  phenomenon  is  particularly  marked  during  running. 

Luciani  has  also  mentioned  that  the  hand  of  the  monkey  (on 
the  operated  side)  is  less  active,  it  takes  hold  of  food  in  a  different 
manner.  A  similar  fact  has  been  noted  by  Lewandowsky ;  the 
movements  of  prehension  are  abnormal,  the  animal  seizes  ah 
object  to  one  side,  or  too  close  to  him,  or  too  far  away,  and  he 
cannot  easily  hold  it  in  his  hand.  The  disturbances  of  the  appro- 
priateness of  the  movements  is  seen  even  when  the  monkey  tries 
to  climb ;  he  seizes  the  bar  between  the  third  and  fourth  fingers. 

Synergy  does  not  appear  to  be  disturbed;  it  is  not  only  direc- 
tion that  the  animal  has  lost,  but  also  the  chronological  sense  of 
its  muscular  contractions.  "  Cerebellar  ataxia  is  a  sensory  ataxia 
which  depends  upon  a  grave  disturbance  of  the  muscular  sense 
entailing  a  loss  of  the  power  to  graduate  the  movements,  and  regu- 
late the  proportional  force,  the  rapidity  and  the  succession  of  mus- 
cular contractions  either  isolated  or  synergically  united :  the  move- 
ments take  a  marked  character  of  non-appropriateness,  i  .  ." 
Lewandowsky  goes  further :  The  cerebellum  is  not  a  stranger  to 
the  perception  of  superficial  excitations.  "  The  loss  of  the  reflex 
of  contact  indicates  a  disturbance  of  cutaneous  sensation." 

The  observations  of  Lewandowsky  have  been  partially  con- 
tested by  H.  Munk.  According  to  his  own  observations  (and 
contrary  to  those  of  Lewandowsky),  the  monkey  only  exception- 
ally seizes  the  bars  of  his  cage  in  an  abnormal  manner.  He  rec- 
ognizes that  the  dog  does  not  always  correct  the  vicious  attitudes 
of  his  body,  or  at  least  corrects  them  more  slowly  than  he  nor- 
mally would,  nevertheless  when  these  attitudes  have  been  arti- 
ficially produced  (as  Ducceschi  and  Sergi  have  noted),  the  cor- 
rection is  sometimes  made  in  a  normal  manner,  and  at  other  times 
with  a  notable  slowness;  often  also,  it  is  true,  that  they  are  only 
incompletely  made.  These  same  authors  also  insist  that  this  phe- 
nomenon is  produced  not  only  on  the  side  of  the  operation,  but 
also  on  the  healthy  side.  They  note  only  that  the  correction  is 


144  THE    FUNCTIONS    OF    THE    CEREBELLUM 

slower  on  the  operated  side.  Besides,  when  the  animal  com- 
mences to  walk  one  is  more  rarely  able  to  impress  upon  the  limbs 
these  abnormal  attitudes. 

To  sum  up,  these  abnormal  attitudes  or  positions  exist ;  the  in- 
terpretation of  them  is  more  delicate.  Lewandowsky  attributes 
them  to  a  loss  of  the  perception  of  the  right  or  wrong  position 
of  the  limbs  and  this  interpretation  at  first  sight  seems  quite 
logical.  However  this  may  be,  the  lack  of,  or  the  slowness 
in,  the  correction  of  these  abnormal  attitudes  attenuates  or 
disappears  with  time,  and  it  is  difficult  to  attach  to  this  temporary 
sign  a  definite  loss  of  the  muscular  sense.  May  not  the  lack  of 
correction  of  these  vicious  attitudes  be  occasioned  by  the  feeling 
of  uncertainty  and  the  tendency  towards  inertia  on  the  part  of 
the  animal?  The  animal  is  conscious  of  its  awkwardness  and 
during  the  first  days  following  the  operation  avoids  moving. 

A  more  serious  criticism  has  been  made  of  Lewandowsky's 
position — which  has  nevertheless  contributed  to  throw  light  upon 
the  disorders  of  the  isolated  movements  of  the  limbs,  but  in  which 
he  is  possibly  wrong,  to  deny  those  of  synergy — that  is,  to  have 
too  much  neglected,  as  also  has  Lussana,  clinical  observations. 
For  in  patients  affected  with  cerebellar  atrophy,  disturbances  of 
deep  sensation  are  altogether  lacking.  Up  to  the  present  no  one 
has  noted  any  perturbation  comparable  to  that  observed  in  the 
affections  of  the  optic  thalamus,  that  is  to  say,  in  the  thalamic 
syndrome  (J.  Dejerine  and  Egger,  Roussy).  One  can  also  re- 
proach him  with  having  envisaged  the  cerebellar  ataxia  as  a 
grave  disturbance  of  the  muscular  sense  and  having  hesitated  as 
to  the  conscious  or  unconscious  nature  of  this  sense.  What  is  an 
unconscious  sense  or  sensibility  anyway? 

One  cannot  deny,  however,  that  the  peripheral  excitations 
which  originate  in  the  trunk,  or  in  the  limbs,  have  a  part  in  the 
mechanism  of  the  cerebellum.  These  excitations  are  transmitted 
to  the  cerebellum  through  the  intermediation  of  the  direct  cere- 
bellar tract  and  the  tract  of  Cowers,  as  noted,  and  section  of 
'these  bundles  gives  rise  to  symptoms  which  have  some  resem- 
blance to  those  which  follow  a  destruction  of  the  cerebellum 
(Bing).  But  these  excitations  are  not  perceived  by  the  cere- 
bellum. , 

On  the  other  hand,  the  cerebellum  receives  through  the  inter- 


THE    CEREBELLUM    AND    MOTILITY  145 

mediation  of  the  pontine  nuclei,  the  crura  cerebri,  and  the  middle 
cerebellar  peduncles,  a  large  number  of  impressions,  which  for 
the  most  part,  are  derived  from  the  sensory  motor  zone  of  the 
cerebral  cortex.  The  cerebellum  therefore  stores  up  impressions 
which  come  to  it  either  directly  from  the  periphery  (spinal  and 
restiform  paths),  or  indirectly  after  having  been  subjected  to  a 
representation  or  an  elaboration,  from  the  cerebral  cortex. 
Mann,  who  considers  the  ataxia  as  one  of  the  principal  cerebellar 
symptoms,  does  not  differentiate  it  in  any  way  from  the  peripheral 
ataxia  or  the  tabetic  ataxia.  In  the  two  cases  the  ataxia  is  due  to 
the  lack  of  or  the  suppression  of  peripheral  excitations  which 
originate  in  the  muscles  at  the  moment  of  their  contraction. 
These  indices  of  muscular  innervation  would  normally  be  re- 
corded in  the  cerebellum  and  rest  below  the  threshold  of  con- 
sciousness. Mann  remarks  that  in  fact  the  execution  of  move- 
ments does  not  give  rise  to  conscious  sensations  of  articular  dis- 
placements, and  is  not  accompanied  by  conscious  sensations  of 
muscular  contractions ;  this  is  why  cerebellar  ataxia  is  not  accom- 
panied by  any  apparent  disturbance  of  sensibility.  The  same  can 
be  the  case  in  peripheral  ataxia. 

This  conception  will  have  to  be  slightly  modified  if  certain 
phenomena,  to  which  Lotmar  has  recently  drawn  attention, 
should  again  be  noted  in  cases  of  lesions  strictly  cerebellar.  In 
two  patients  presenting  a  clinical  syndrome  very  comparable  with 
that  of  cerebellar  lesions  (in  one  case  it  was  a  question  of  cere- 
bellar apoplexy,  and  in  the  other  a  lesion  of  the  tegmentum  of  the 
crus  cerebri  affecting  the  superior  cerebellar  peduncle),  Lotmar 
observed  a  disturbance  of  deep  sensibility  consisting  of  a  defect 
in  the  estimation  of  weight. 

The  weights  were  contained  in  a  pasteboard  box  and  placed 
in  the  hollow  of  the  hand,  the  two  elbows  being  symmetrically 
supported,  and  the  forearm  in  supination ;  the  patient  was  told  to 
estimate  the  weight  in  the  right  hand  in  comparison  with  that  in 
the  left  by  slowly  weighing  them  in  the  hands.  On  the  side  of 
the  cerebellar  hemi-ataxia  the  weights  were  estimated  below  their 
real  value;  on  the  other  hand  the  notions  of  displacement,  posi- 
tion and  sensibility  to  pressure  and  stereognosis  were  intact. 
Making  every  reserve  as  to  the  location  of  the  lesions,  which  was 
ii 


146  THE    FUNCTIONS    OF    THE    CEREBELLUM 

not  verified  by  an  autopsy  in  either  of  these  cases,  Lotmar  con- 
cludes that  the  cerebellum  should  be  envisaged  as  a  central  organ, 
and  as  a  relay  station,  not  for  all  modes  of  deep  sensation,  but  for 
those  excitations  which  result  in  variations  of  tension  in  con- 
tracted muscles. 

Hitzig  has  expressed  a  very  similar  opinion:  The  cerebellum 
with  the  subcortical  organs,  which  are  annexed  to  it  groups  the 
peripheral  impressions  coming  from  various  sources,  forms  of 
them  representations  of  an  inferior  order  which  it  then  transmits 
as  a  whole  to  the  cerebrum.  This  alone  would  be  capable  of 
utilizing  the  impressions  as  a  whole,  but  it  would  not  be  -able  to 
penetrate  into  each  unit  of. these  impressions,  which  would  rest 
below  the  threshold  of  consciousness.  The  cerebrum  has  a  dif- 
ferent action  from  the  cerebellum  in  the  sense  that  it  delivers  con- 
scious intentional  impulses,  which  are  divided  afterwards  by  the 
cerebellum  for  each  particular  motor  center. 

To  sum  up:  It  has  not  been  demonstrated  that  the  cerebellum 
is  an  organ  of  perception  for  deep  sensation  which  is  currently 
designated  by  the  name  of  "  muscular  sense." .  It  is  legitimate  to 
admit,  however,  that  it  utilises  the  oscillations  of  nervous  flux 
which  take  their  source  in  the  displacements  of  the  deep  parts, 
and  the  variations  of  muscular  contraction  or  tonicity. . 

As  to  cerebellar  ataxia,  it  is,  in  my  opinion,  in  no  way  identical 
with  tabetic ;  ataxia.  Not .  only  is  the  disturbance  of  tonicity  not 
the  same  in  the  two  cases,  but  they  differ  from  one  another  by  the 
absence  of  disturbances  of  deep  sensibility  in  the  first,  and  by 
their  extreme  frequency,  not  to  say  constancy,  in  the,  second. 
The  observations  upon  which  Mann  bases,  his  contention  are  for 
the  most  part  observations  of  a  complex  nature,  and  in  which  the 
lesion  has  interrupted  other  than  purely  cerebellar  paths. 


THE  CEREBELLUM  AND  MOTILITY  147 

ARE  THE  PHENOMENA  OBSERVED  AFTER  TOTAL  OR  PARTIAL  DE- 
STRUCTION  OF   THE   CEREBELLUM,   ALL  OF  THE   SAME 
ORDER?     Is  THERE  REASON  TO  DISTINGUISH   BE- 
TWEEN THE  IMMEDIATE  IRRITATIVE  PHENOMENA 
AND  THE  LATER  ONES  DUE  TO  THE  IMPERFEC- 
TION OR  LACK  OF  CEREBELLAR  INNERVATION  ? 
THE  CAUSE  OF  THE  MOVEMENTS  OF 
ROLLING  OR  ROTATION. 

The  partial  or  total  experimental  destructions  of  the  cere- 
bellum determine,  according  to  Luciani,  two  types  of  phenomena : 
(i)  Immediate  phenomena  due  to  irritation.  (2)  Subsequent 
phenomena  due  to  imperfection  or  lack  of  cerebellar  innervation. 

The  phenomena  considered  by  Luciani  as  irritative  phenom- 
ena are  the  following: 

(i) Unilateral  Destruction. — Pleurosthotonus,  or  the  incur- 
vation of  the  vertebral  arc  towards  the  side  operated  upon,  asso- 
ciated with  the  tonic  extension  of  the  forward  limb  of  the  same 
side  (in  the  dog),  and  with  clonic  movements  of  the  three  other 
limbs.  A  contortion  of  the  vertebral  axis  in  a  spiral  fashion, 
principally  in  the  cervical  region,  towards  the  healthy  side,  asso- 
ciated with  strabismus  and  unilateral  (sometimes  bilateral)  nys- 
tagmus (deviation  of  the  eye  of  the  side  operated  upon,  inwards 
and  downwards,  and  of  the  other  eye  outwards  and  upwards). 
A  tendency  to  rotation  around  the  longitudinal  axis  according 
to  the  direction  of  the  torsion  and  the  strabismus,  that  is,  from  the 
operated  to  the  healthy  side.  These  movements  are  not  con- 
stantly produced  except  during  the  first  days,  they  do  not  become 
exaggerated  the  following  days  except  when  the  animal  is  ap- 
proached or  excited,  or  when  it  attempts  to  walk. 

(2)  Total  Destruction. — Incurvation 'backwards  of  the  verte- 
bral column  in  the  form  of  opisthotonus,  tonic  extension  of  the 
two  forward  limbs  with  clonic  movements  of  the  hind  limbs  and 
bilateral  convergence  of  the  eyeballs.  A  tendency  to  draw  back 
and  fall  backwards.  These  symptoms  are  at  first  continuous, 
afterwards  they  do  not  arise  except  intermittently  when  the 
animal  is  excited,  or  when  'it  attempts  a  voluntary  act. 

In  both  cases  (partial  or  total  destruction),  we  must  add  to 
the  irritative  phenomena :  Agitation,  restlessness,  and  the  frequent 
whining  of  the  animal. 


148  THE    FUNCTIONS    OF  'THE    CEREBELLUM 

This  shows,  according  to  Luciani,  that  these  phenomena  de- 
pend upon  irritation  of  the  efferent  fibers  which  compose  the 
cerebellar  peduncles,  that  is,  that  in  an  animal  which  has  been 
subjected  to  an  extirpation  of  the  median  lobe  of  the  cerebellum 
some  time  back,  and  in  which  many  of  the  fibers  of  these 
peduncles  have  undergone  degeneration,  and  consequently  lost 
their  excitability,  if  then  a  hemisphere  is  removed,  the  phenomena 
are  of  a  much  lighter  character  and  more  evanescent  than  if  the 
operation  had  been  made  in  one  stage  upon  another  animal. 

This  interpretation  is  very  debatable,  and  the  diminution  in 
the  intensity  of  the  so-called  immediate  phenomena,  after  the 
second  operation,  can  be  just  as  well  explained  by  a  certain  habit- 
uation  and  by  cerebral  substitution  upon  which  Luciani  has  so 
rightly  insisted,  to  account  for  the  reeducation  of  the  animal  de- 
prived partially  or  totally  of  the  cerebellum. 

Luciani  has  devoted  a  long  and  critical  study  to  the  move- 
ments of  rolling  or  rotation  around  the  longitudinal  axis  de- 
scribed for  the  first  time  by  Parfour  du  Petit,  and  observed  by 
Magendie,  Lafargue,  Schiff,  Longet  and  Vulpian. 

Physiologists  have  been  for  a  long  time  in  disaccord  as  to 
the  direction  of  the  movements  which  follow  lesions  of  the  cere- 
bellum, or  of  the  cerebellar  peduncles,  possibly  because  they  have 
not  agreed  sufficiently  well  as  to  the  manner  of  describing  the 
direction  of  rotation. 

According  to  Magendie  the  rolling  takes  place  from  the 
healthy  side  towards  the  side  operated  upon ;  according  to  Longet, 
in  the  opposite  direction.  Schiff  has  attempted  to  explain  these 
contradictory  results  by  the  difference  in  the  technique  of  the 
authors  in  doing  the  operations.  Magendie  appears  to  have  sec- 
tioned the  inferior  peduncle  of  the  same  side;  Longet  not  only 
sectioned  a  cerebellar  hemisphere  but  also  the  inferior  cerebellar 
peduncle  of  the  opposite  side  (which  he  wrongly  considered 
formed  of  crossed  fibers  in  the  white  substance  of  the  cerebellum). 
Schiff  has  brought  to  light  another  fact  of  great  value.  He 
observed  that  if  the  rabbit  (it  was  upon  this  animal  that  he 
made  the  demonstration)  is  left  free  at  the  moment  of  section 
of  the  peduncle,  he  executes  at  first  two  or  three  rolling  move- 
ments from  the  operated  side  towards  the  healthy  side,  and  after- 
wards a  whole  series  of  movements  in  the  opposite  direction ; 


THE    CEREBELLUM    AND    MOTILITY  149 

the  first  movements  would  be  due  to  irritation  and  the  second 
to  paralysis.  Section  of  the  middle  cerebellar  peduncle  would 
place  an  obstacle  to  the  passages  of  the  voluntary  influx  to  the 
muscles  of  the  vertebral  column  of  one  side. 

Contrary  to  the  hypothesis  given  out  by  Serres  and  Lafargue, 
the  limbs  would  not  play  any  part,  or  at  least  any  prominent  part, 
in  the  production  of  the  phenomenon  because  it  takes  place  just 
as  well  when  the  posterior  limbs  are  immobilized  or  paralyzed  by 
section  of  the  sciatic  nerve.  Nevertheless,  Schiff  contests  the 
theory  of  Henle,  Gratiollet  and  Leven  who  attributed  the  move- 
ment of  rotation  to  an  optic  vertigo :  the  phenomenon  takes  place 
just  the  same  in  blind  animals  as  in  those  which  can  see. 

Luciani  admits  also  that  movements  of  rotation  take  place  * 
after  section  of  the  peduncle  at  first  towards  the  healthy  side,  and 
afterwards  in  the  opposite  direction.  The  first  movements  to- 
wards the  healthy  side  are  engendered  by  the  unilateral  exagger- 
ation of  the  cerebellar  influx  transmitted  to  the  irritated  peduncle, 
whereas,  the  others  are  produced  in  the  opposite  direction  because 
the  cerebellar  influx  suddenly  ceases  to  exist  in  half  of  the  centers, 
while  the  other  half  continues  to  receive  them.  The  predomi- 
nance of  the  action  of  half  the  centers  is  the  necessary  condition, 
and  the  impression  of  vertigo  is  the  immediate  cause.  Luciani 
admits,  however,  that  the  phenomenon  of  rolling  can  exist  without 
vertigo,  but  the  vertiginous  movements  seem  to  have  the  char- 
acter of  impulsive  and  irresistible  movements.  The  movements 
of  simple  functional  predominance  of  half  of  the  encephalon 
would  have  the  character  of  ordinary  voluntary  or  reflex  move- 
ments. But  Luciani  attacks  the  fundamental  conception  of 
Schiff  for  whom  the  movement  of  rotation  is  due  to  the  unilateral 
interruption  of  voluntary  impulses  to  the  rotatory  and  fixing  mus- 
cles of  the  vertebral  axis :  The  cerebellum  is  not  an  organ  of  the 
will,  that  is  to  say,  an  organ  intercalated  in  the  great  path  of  cere- 
bro-spinal  conduction. 

Nevertheless,  in  animals  from  which  he  had  removed  half 
the  cerebellum,  Luciani  observed  movements  in  only  one  direction, 
that  is,  towards  the  healthy  side,  movements  which  he  had  ob- 
served during  the  phase  of  excitation,  and  which  he  considered 
as  irritative  phenomena.  The  movements  of  rotation  in  the  op- 
posite direction  would  not  have  been  avoided  except  for  the  inter- 


I5O  THE    FUNCTIONS    OF    THE    CEREBELLUM 

vention  of  the  muscular  sense,  and  the  proof  is  that  if  the  mus- 
cular sense  and  the  motor  impulse  be  suppressed  by  destroying 
a  part  of  the  sensory-motor  area,  the  animal  is  seen  at  every 
effort  to  walk,  to  roll  around  the  longitudinal  axis  towards  the 
side  upon  which  the  cerebellum  is  lacking.  Upon  this  point  my 
own  experience  does  not  coincide  with  that  of  Luciani. 

Besides,  in  the  dog,  according  to  Luciani,  it  is  not  only  the 
muscles  of  the  vertebral  axis  which  contribute  to  the  production 
of  the  rolling,  those  of  the  limbs  have  also  their  part. 

The  opinion  of  Luciani  which  I  have  just  cited,  almost  word 
for  word,  does  not  appear  to  me  to  be  acceptable,  and  for  several 
reasons.  Luciani  considers  the  movements  of  rolling  which  he 
observed  in  dogs,  as  movements  due  to  irritation  of  the  peduncle ; 
we  must  recall  that  the  animals  Luciani  operated  upon  were  anes- 
thetised  and  that  the  movements 'which  he  calls  irritative  were 
not  produced  until  after  the  awakening  of  the  animal.  I,  also, 
operated  upon  animals  under  an  anesthetic,  but  in  some  cases 
the  anesthesia  was  not  complete  when  I  removed  the  cerebellum 
and  sectioned  the  peduncles.  I  then  observed,  exactly  at  that 
time,  some  movements  of  rotation  in  the  opposite  direction  to 
those  which  I  observed  upon  the  awakening  of  the  animal.  These 
results  may  be  compared  with  those  obtained  by  Schiff  when  he 
sectioned  the  peduncles.  The  first  movements  which  are  irrita- 
tive movements,  provoked  by  section  of  the  peduncle,  are  alto- 
gether comparable  to  the  muscular  contraction  which  is  produced 
when  an  anterior  root  is  sectioned;  those  which  take  place  after 
the  awakening  are  paralytic  movements,  that  is  to  say,  due  to  the 
suppression  of  the  cerebellar  function.  It  is  these  that  Luciani 
has  mistaken  for  irritative  phenomena.  He  did  not  take  into 
account  the  fact  that  the  really  irritative  movements  were  masked 
by  the  narcosis.1 

It  is  enough,  besides,  as  I  have  already  remarked  in  my  thesis, 
to  follow  the  evolution  of  the  disorders  of  locomotion  to  thor- 
oughly understand  the  nature  of  the  phenomena.  "When 

1  Luciani  says  that  in  animals  the  rotation  around  the  longitudinal  axis 
is  made  from  the  operated  side  towards  the  healthy  side,  but  he  determined 
the  sense  of  rotation  according  to  the  direction  and  torsion  of  the  head, 
and  the  strabismus;  the  results  which  he  obtained,  therefore,  accord  per- 
fectly with  ours. 


THE    CEREBELLUM    AND    MOTILITY  15! 

half  the  cerebellum  has  been  destroyed,  whatever  be  the  atti- 
tude that  the  animal  wishes  to  take,  and  whatever  be  the  move- 
ment that  he  wishes  to  execute,  he  is  drawn  towards  the  side  of 
the  lesion  and  falls  on  that  side.  The  first  days  after  the  opera- 
tion he  is  animated  with  movements  of  rotation  around  the  lon- 
gitudinal axis  from  the  healthy  side  towards  the  side  operated. 
(The  sense  of  the  rotation  is  determined  by  the  side  upon  which 
the  animal  falls  when  he  is  placed  in  an  upright  station,  i.  e.,  when 
he  is  placed  upon  his  four  paws.  As  he  always  falls  upon  the 
operated  side  one  may  say  that  the  rotation  takes  place  from  the 
healthy  side  towards  the  side  operated.)  In  repose  he  rests  upon 
the  side  of  the  lesion,  and  in  the  abdominal  decubitus  the  head  is 
deviated  in  the  same  direction.  Later,  when  he  makes  his  first 
attempts  to  walk  he  is  drawn  in  spite  of  himself  by  a  movement 
of  translation  towards  the  operated  side,  and  if  he  falls,  he  falls 
on  this  side.  It  seems,  therefore,  that  the  rotation  around  the 
longitudinal  axis  from  the  healthy  side  towards  the  side  operated 
upon,  the  decubitus  upon  the  side  of  the  lesion,  the  fall  and  the 
movement  of  translation  in  the  same  direction  are  but  different 
degrees  of  the  same  phenomenon.  If  the  movement  of  rotation  is 
due  to  the  irritation  of  the  efferent  fibers  which  have  been  cut, 
there  should  be  a  different  direction  of  the  movements  consecutive 
to  the  suppression  of  these  fibers,  and  they  should  be  made  from 
the  operated  side  towards  the  healthy  side." 

We  see  how  involved  is  this  question  of  the  movements  of  ro- 
tation, not  only  as  concerns  the  fact  itself  and  its  nature,  but 
also  as  regards  the  terminology  and  manner  of  indicating  the  di- 
rection of  the  movement.  Perhaps  these  last  explanations  will 
permit  us  to  understand  this  phenomenon,  and  the  contradic- 
tions to  which  it  has  given  rise,  more  thoroughly.  The  physio- 
logical mechanism  of  the  movements  of  rotation  of  the  body,  as 
well  as  those  of  the  conjugate  deviation  of  the  eyes,  may  be 
cleared  up  in  a  certain  measure  by  the  knowledge  which  we  have 
acquired  in  the  last  few  years  concerning  the  architecture  and  the 
anatomical  relations  of  the  cerebellum. 

The  tonic  action  of  the  cerebellum  is  exercised  in  the  case 
of  the  vermis  by  the  intermediation  of  the  descending  cerebellar 
bundle,  the  cerebello-vestibular  bundles,  and  the  nucleus  of  the 
vestibular  nerve,  in  relation  to  the  spinal  cord;  for  the  hemi- 


152  THE    FUNCTIONS    OF    THE    CEREBELLUM 

spheres  by  the  intermediation  of  the  superior  cerebellar  peduncle 
and  the  red  nucleus;  upon  the  spinal  column  (the  rubro-spinal 
bundle)  by  the  intermediation  of  the  superior  cerebellar  peduncle 
and  the  thalamus  upon  the  cerebral  cortex  (thalamo-cortical 
fibers). 

Each  half  of  the  vermis  enters  into  relation  with  the  nuclei 
of  the  two  vestibular  nerves,  and  with  the  two  sides  of  the  spinal 
column,  but  more  with  the  same  side  by  the  cerebello-vestibular 
bundles.  It  is  probable  that  each  half  of  the  vermis  does  not  con- 
tract the  same  relations  with  the  two  sides  of  the  spinal  column, 
and  consequently,  presides  over  a  certain  coordination. 

Each  nucleus  of  Deiters  sends  fibers  to  the  oculo-motor  nuclei, 
particularly  to  the  nucleus  of  the  sixth  pair  of  the  same  side, 
to  the  nucleus  of  the  third  pair  of  the  opposite  side,  to  the  centers 
of  the  muscles  of  the  trunk,  and  the  limbs  of  the  same  side 
(posterior  longitudinal  fasciculus  and  antero-lateral  bundle). 

When  the  cerebello-vestibular  bundles  are  interrupted  on  one 
side,  a  conjugate  deviation  of  the  eyes  results,  such  that  the  eye 
of  the  side  of  the  lesion  looks  downward  and  inward,  and  that  of 
the  opposite  side  looks  upward  and  outwards.  There  is  a  devia- 
tion of  the  head  in  the  same  direction,  and  a  movement  of  rota- 
tion from  the  healthy  side  towards  the  operated  side.  This  total- 
ity of  phenomena  does  not  differ  in  any  way  from  that  which  is 
obtained  from  exciting  the  nucleus  of  Deiters-Bechterew  on  the 
side  opposite  the  lesion.  One  may  admit  that  in  the  normal  state 
the  forces  developed  by  the  two  nuclei  of  Deiters  balance  one 
another.  If  one  of  them  disappears  or  is  diminished  in  large  meas- 
ure on  account  of  the  suppression  of  the  cerebello-vestibular 
bundles  of  one  side,  the  other,  continuing  to  act,  produces  symp- 
toms analogous  to  those  obtained  by  the  excitation  of  the  homo- 
lateral  nucleus  of  Deiters-Bechterew.  We  may  reason  in  the 
same  way  concerning  the  olivo-thalamo-cortical  path  (superior 
cerebellar  peduncle,  thalamus  and  cerebral  cortex),  and  for  the 
olivo-rubro-spinal  path.  The  results  of  section  of  the  superior 
cerebellar  peduncle  justify  this  point  of  view. 

Is  THE  CEREBELLUM  A  CENTER  OF  MUSCULAR  ENERGY? 

Based  upon  numerous  experiments  made  upon  animals  belong- 
ing to  four  types  of  vertebrates,  Rolando  attempted  to  demon- 


THE    CEREBELLUM    AND    MOTILITY  153 

strata  that  the  cerebellum  was  an  organ  destined  for  the  prepara- 
tion and  secretion  of  nervous  energy,  which  diversely  conducted 
and  modified  manifested  itself  principally  in  the  production  of 
motion  and  of  voluntary  movements.  Partial  alterations  of  it 
gave  rise  to  disturbances  of  voluntary  movements,  complete  de- 
structions to  total  paralysis.  The  cerebellum  would  have  even  a 
greater  part  than  the  cerebrum  in  the  phenomena  of  motility. 
In  placing  one  of  the  poles  of  a  battery  in  contact  with  the  cere- 
bellum and  the  other  with  a  limb,  stronger  shocks  were  obtained 
than  if  the  first  pole  were  placed  upon  the  cerebrum.  This  in- 
fluence, however,  did  not  belong  properly  to  it — it  borrowed  it 
either  from  the  senses  or  from  the  hemispheric  excitations.  Tak- 
ing microscopical  examination,  on  the  other  hand,  into  considera- 
tion, Rolando  thought  that  the  large  number  of  lamellae,  alter- 
nately gray  and  white  were  an  electric  battery  which  developed 
electricity  which  excited  movements. 

This  theory  was  criticised  by  Magendie.  He  did  not  deny  the 
facts  announced  by  Rolando,  but  he  did  not  accept  the  explana- 
tion for  he  had  seen  animals  deprived  of  the  cerebellum  "  which 
nevertheless  executed  very  vigorous  movements.  I  have  seen 
hedgehogs  and  guinea-pigs  deprived  not  only  of  their  cerebrum, 
but  also  of  their  cerebellum  scratch  their  noses  with  their  fore 
paws  when  I  placed  a  bottle  of  vinegar  under  their  noses.7' 

The  theory  sustained  later  by  Luciani  presents  some  marked 
analogies  with  that  of  Rolando.  Once  the  irritative  phenomena 
have  subsided,  the  Florentine  physiologist  distinguishes  two 
orders  of  phenomena,  the  phenomena  of  suppression  and  the 
phenomena  of  compensation. 

The  suppression  is  essentially  characterized  by  the  imperfect 
energy  that  the  animal  uses  in  its  voluntary  acts,  by  the  lack  of 
tonicity  of  the  muscles,  and  by  the  abnormal  method  of  their 
contraction. 

Luys  also  considered  the  general  state  of  weakness,  and  the 
progressive  extinction  of  muscular  power  as  a  disturbance  char- 
acteristic of  the  locomotor  functions  in  individuals  affected  with 
lesions  of  the  cerebellum. 

This  weakness  "  may  present  an  infinite  number  of  degrees, 
from  a  simple  lassitude  to  a  profound  prostration  with  the  most 
complete  apathy.  The  movements  are  sometimes  not  harmonic, 


154  THE    FUNCTIONS    OF    THE    CEREBELLUM 

but  hardly  ever  completely  abolished.  There  is  asthenia  and  not 
paralysis." 

After  the  destruction  of  the  cerebellum  by  caustics  Weir 
Mitchell  observed  -the  phenomena  of  incoordination,  drawing 
back,  and  backward  falls,  but  these  phenomena  were  of  short 
duration.  That  which  persisted  was  a  well  marked  weakness 
of  all  movements,  whether  voluntary  or  involuntary.  The  cere- 
bellum would  then  be  an  organ  of  reinforcement,  the  action  of 
which  would  be  very  analogous  to  that  of  the  spinal  and  cerebral 
ganglionic  masses. 

Dalton  insisted  also  upon  the  persistence  of  weakness  when 
the  phenomena  of  the  first  stage  had  disappeared. 

Dupuy  sustained  a  similar  opinion:  If  a  complete  ablation  of 
the  cerebellum  were  made,  the  peduncles  sectioned  entirely  and  at 
the  same  level,  and  the  whole  operation  done  at  one  time,  there 
were  no  locomotor  symptoms  in  the  animal  experimented  upon 
(dog,  rabbit,  and  guinea  pig).  The  most  striking  thing  was  the 
extreme  weakness  in  the  movements  of  the  individual  as  a  whole, 
and  even  comparing  the  weakness  which  follows  the  ablation  of 
the  cerebral  lobes  with  that  consecutive  to  the  ablation  of  the 
cerebellum,  one  is  surprised  to  see  that  the  animal  preserves  more 
strength  in  the  first  case  than  in  the  latter. 

The  compensatory  acts  consist  according  to  Luciani,  in  the 
isolated  form  of  the  voluntary  movements,  in  the  anomalies  of 
measure  and  direction.  The  totality  of  these  phenomena  con- 
stitutes cerebellar  ataxia. 

After  the  unilateral  destruction  the  weakness  is  such  in  the 
muscles  on  the  side  of  the  operation  that  the  animal  might  be 
taken  for  a  hemiplegic;  he  drags  himself  along  the  rump  of  the 
side  operated  upon  making  his  efforts  with  the  limbs  of  the 
healthy  side.  This  condition  may  last  for  several  weeks,  accord- 
ing to  Luciani.  By  leaning  against  a  wall  the  animal  may  move 
in  a  regular  manner,  but  his  limbs  bend  under  his  own  weight. 
The  animal  can,  however,  swim,  but  the  flank  of  the  side  operated 
upon  is  always  plunged  deeper  in  the  water  than  that  of  the 
healthy  side.  The  same  phenomena  are  observed  for  a  month 
or  more,  during  which  time  the  animal  makes  various  attempts 
to  get  up  and  walk.  These  attempts  are  the  manifestations  of 
the  compensatory  acts  which  are  capable  of  correcting  and  repair- 


THE    CEREBELLUM    AND    MOTILITY  155 

ing  the  effects  of  the  suppression  of  the  cerebellum.  The  animal 
broadens  its  base  of  support  by  spreading  the  front  limbs  apart, 
particularly  the  one  on  the  injured  side  and  the  vertebral  column 
is  incurved  towards  this  side. 

This  compensation  has  its  limit.  The  animal  which  walks 
in  this  way  on  a  smooth  surface  cannot  walk  upon  a  rough  or 
curved  surface.  When  food  is  offered  to  it,  if  it  is  held  a  cer- 
tain distance  above  the  head,  the  animal  attempts  to  rise  up  ver- 
tically, but  falls  back  on  account  of  the  flexion  of  the  posterior 
limbs.  If  it  is  made  to  pull  a  weight  tied  to  the  tail  or  to  the 
limbs,  its  fall  is  almost  certain,  particularly  if  the  weight  is  tied 
to  the  limbs  of  the  heathy  side. 

Luciani  concludes  from  this  that  the  lack  of  innervation  from 
one  half  of  the  cerebellum  determines  a  homonomous  neuro-mus- 
cular  hemiasthenia.  There  is  a  diminution  of  the  normal  tonus  of 
the  muscles,  on  palpation  the  muscles  appear  to  be  more  flaccid, 
and  less  tense  on  the  side  of  the  operation  than  on  the  healthy  side. 
This  is  asthenia. 

During  station  upon  the  four  paws  the  animal  often  flexes  the 
limbs  of  the  side  operated  upon.  The  falls  seem  to  be  due  to  the 
relaxing  of  the  muscles.  He  raises  the  paws  of  the  injured  side 
higher  from  the  ground,  and  replaces  them  more  suddenly.  To 
this  second  category  of  phenomena  Luciani  gives  the  name  of 
atonia. 

Finally,  there  exists  tremor,  oscillations  and  wavering  which 
depend  upon  an  imperfect  summation  of  the  elementary  impulses 
which  govern  contraction.  This  third  category  of  phenomena 
constitutes  astasia. 

In  animals  completely  deprived  of  the  cerebellum,  atonia, 
asthenia  and  astasia  are  still  more  marked.  After  a  period  dur- 
ing which  the  animal  falls  continually,  first  on  one  side  and  then 
on  the  other,  striking  the  head,  he  succeeds  at  first  in  raising  the 
front  paws,  but  the  hind  paws  bend  under  him.  When  the  animal 
tries  to  eat,  his  body  is  animated  by  strong  antero-posterior  oscil- 
lations. Little  by  little,  he  succeeds  in  walking  without  falling, 
and  progressing  without  help.  These  phenomena  are  not  caused 
by  a  lack  of  coordination  says  Luciani,  because  the  animals  are 
able  to  swim.  The  functional  restitution  which  gradually  is  pro- 
duced is  due  entirely  to  a  substitution  by  the  sensory-motor  zone 
of  the  cerebral  cortex  when  the  extirpation  has  been  total. 


156  THE   FUNCTIONS   OF   THE   CEREBELLUM 

The  falls  are  due  to  the  atonia  and  the  asthenia  of  the  muscles 
of  the  vertebral  column  which  cause  a  greater  upward  convexity 
of  the  vertebral  axis,  and  determine  thus  an  elevation  of  the 
center  of  gravity,  and,  consequently,  a  loss  of  stability  of  equilib- 
rium. There  results  also  a  lesser  fixity  of  the  vertebral  axis 
which  renders  the  horizontal  oscillations  either  active  or  passive, 
more  difficult  to  resist.  Luciani  does  not  see  in  the  drunken  gait 
any  perturbation  of  the  sense  of  equilibrium.  The  efficacy  of 
the  compensatory  acts  by  means  of  which  the  animal  avoids  a  fall, 
shows  on  the  contrary  that  this  sense  functions  normally. 

Luciani  concludes,  from  his  experiments,  and  the  anatomical 
findings  furnished  by  the  study  of  secondary  degenerations,  that 
the  cerebellum  is  an  homogenous  organ.  An  organ  of  which 
each  segment  has  the  same  function  as  the  whole,  and  the  power 
of  supplying  the  absence  of  the  others.  The  loss  of  the  vermis 
may  thus  be  compensated  for  by  the  lateral  lobe.  The  cerebellum 
exercises,  in  the  normal  condition,  an  influence  upon  the  rest  of 
the  nervous  system,  which  is  expressed  by  an  action,  neuro-mus- 
cular,  sthenic,  tonic  and  static,  that  is  to  say,  a  complex  action  by 
which  the  cerebellum  augments  the  potential  energy  which  is  dis- 
pensed by  the  neuro-muscular  apparatus  (sthenic  action).  It  in- 
creases the  duration  of  their  tension  during  the  functional  pause 
(tonic  action)  ;  it  accelerates  the  rhythm  of  the  elementary  im- 
pulses during  their  functional  activity  and  assures  a  normal  fusion 
and  regular  continuity  of  action  (static  action).  The  influence 
of  the  cerebellum  does  not  alone  manifest  itself  upon  those  mus- 
cles which  enter  into  activity  in  the  different  forms  of  upright 
station  and  locomotion,  but  also  in  all  voluntary  movements,  par- 
ticularly those  of  the  superior  and  inferior  limbs,  and  upon  those 
muscles  which  fix  the  vertebral  column. 

The  complex  action  of  the  cerebellum  is  a  trophic  action, 
which  is  exercised  directly  or  indirectly.  Directly  it  is  shown  by 
the  secondary  degenerations ;  indirectly  it  affirms  itself  by  the  slow 
degeneration  of  the  muscles  and  the  skin,  by  the  general  or  local 
dystrophic  troubles,  by  a  greater  slowness  in  the  growing  and  the 
renewing  of  the  tissues,  by  a  diminution  of  the  resistance  of  the 
animal  against  the  harmful  actions  of  external  agents,  and,  finally 
by  a  general  shortening  of  life. 

The  activity  of  the  cerebellum  is  not  an  activity  sui  generis  but 


THE    CEREBELLUM    AND    MOTILITY  157 

rather  an  activity  common,  and  so  to  say,  fundamental,  to  the 
whole  nervous  system.  The  physiological  value  of  the  cerebellum 
in  the  animal  life  is  quite  comparable  to  the  value  of  the  peripheral 
nerve  ganglia  in  the  vegetative  life.  The  cerebellum  may  be 
considered  as  a  small  auxiliary  and  reenforcing  system  of  the 
great  cerebro-spinal  system. 

"  Finally  if  it  were  shown  that  dysmetria  were  a  constant 
phenomenon,  it  would  be  necessary  to  add  to  the  sthenic,  static, 
and  tonic  effects,  an  action  of  accommodation,  "umpassen  de 
Wirkung,"  upon  which  would  depend  the  proper  measure,  the 
precision,  and  the  accommodation  to  the  object  in  view,  of  the 
different  voluntary,  automatic  or  reflex  acts." 

The  ideas  of  Luciani  have  not  been  universally  accepted,  and 
some  objections  may  be  made  to  them.  Some  in  relation  to  the 
facts,  and  others  to  the  interpretation  of  them. 

The  observations  of  Luciani  agree,  for  the  most  part,  with 
those  that  other  physiologists  have  made  in  repeating  his  experi- 
ments. Nevertheless,  if  I  may  be  allowed  to  bring  in  my  personal 
experience,  I  would  remark  that  reeducation  has  been  less  slow 
with  my  animals  than  with  Luciani's.  In  the  dog  deprived  of 
half  the  cerebellum,  the  weakness  has  never  been  such  that  the 
animal  could  have  been  taken  for  a  hemiplegic,  or  that  at  any 
advanced  period  he  sank  down  under  his  own  weight  when  he 
tried  to  stand  up  on  his  hind  legs  to  seize  food.  Animal  fell 
on  one  side  or  backwards,  but  contrary  to  what  Luciani  says,  the 
fall  was  not  due  to  the  flexion  of  the  hind  legs.  The  animals 
operated  upon  by  Luciani  seem,  therefore,  to  have  been  weaker 
than  those  operated  upon  by  other  physiologists  and  by  myself. 
Perhaps  in  the  course  of  his  experiments,  Luciani  injured  centers 
in  the  neighborhood  of  the  cerebellum,  particularly  those  of  the 
pons.  To  the  support  of  this  explanation  we  may  mention  the 
secondary  degenerations  studied  by  Marchi  in  the  animals  upon 
which  Luciani  had  operated.  The  degenerations  in  the  spinal 
cord  pass  the  limits  of  those  which  are  produced  by  lesions  strictly 
limited  to  the  cerebellum.  They  included  a  bundle  situated  in  the 
lateral  column,  and  which  was  none  other  than  the  rubro-spinal 
bundle,  or  bundle  of  Monakow,  that  is  to  say,  a  bundle  which 
comes  from  the  red  nucleus  and  passes  through  the  pons. 

It  is  probable  that  the  diffusion  of  destructive  lesions  upon 


158  THE   FUNCTIONS   OF   THE   CEREBELLUM 

the  organs  of  the  neighborhood  is  the  reason  why  there  was  a 
greater  intensity  of  the  symptoms  and  a  paralytic  weakness  in 
Luciani's  animals. 

Nevertheless,  Patrizi  contends  that  the  movements  of  protec- 
tion are  less  energetic  upon  the  side  corresponding  to  that  of  the 
cerebellar  hemisphere  which  has  been  removed  in  the  dog.  To 
demonstrate  this  fact  he  suspended  weights  from  the  hind  legs 
after  having  fixed  the  trunk  and  the  fore  legs;  then  he  excited 
the  skin  of  the  back  by  means  of  a  faradic  current ;  on  the  oper- 
ated side  the  weight  was  not  lifted  so  high.  The  same  was  the 
case  when  the  muscle  was  directly  excited,  which  the  author 
explains  by  a  diminution  of  tonus. 

Longet  had  already  remarked,  in  opposition  to  the  theory  of 
Rolando,  that  after  the  operation  on  the  cerebellum  in  birds  and  in 
young  mammals  Rolando  himself  had  always  seen  these  animals 
still  perform  energetic  but  incoordinate  movements  with  their 
four  limbs. 

The  cocks  from  which  Laborde  removed  the  cerebellum,  lifted 
without  trouble  somewhat  heavy  weights  suspended  from  their 
claws.  When  the  paw  of  a  decerebellated  .animal  is  pulled,  even 
on  the  injured  side,  he  retracts  it  with  energy.  Asthenia,  in  the 
sense  which  Luciani  gives  to  it,  is  altogether  lacking;  the  giving 
way  of  the  legs  is  not  a  part  of  the  symptomatology  of  cerebellar 
affections. 

In  patients  affected  with  cerebellar  atrophy  without  a  cerebral 
or  spinal  lesion  at  the  same  time,  there  is  no  paralysis. 

I  have  never  observed  muscular  relaxation  or  hypotony  in  the 
sense  which  is  given  it  by  clinicians,  in  the  patients  which  I  have 
had  an  opportunity  to  examine.  The  sthenic  or  tonic  action  of 
each  half  of  the  cerebellum  upon  the  corresponding  half  of  the 
body  nevertheless  exists,  but  it  appears  to  me  adapted  for  a 
certain  purpose,  that  is,  the  maintenance  of  equilibrium. 

On  the  other  hand,  when  Luciani  attributed  the  tremor,  the 
oscillation,  and  the  wavering,  to  an  imperfect  summation  of  ele- 
mentary impulses,  he  furnished  an  explanation  which  is  more  con- 
formable to  reality. 

For  certain  authors,  Adamkiewicz,  among  others,  the  cere- 
bellum is  more  than  a  regulator.  It  is  an  organ,  the  action  of 
which  assures  the  execution  of  all  of  the  movements  of  the  body, 


THE    CEREBELLUM    AND    MOTILITY  I  59 

of  which  the  will  assures  the  initiation.  It  not  only  elaborates  the 
force  which  is  transformed  into  movements  in  the  muscles — it 
contains  also  a  particular  center  for  each  group  of  muscles,  and 
for  all  a  sort  of  keyboard  upon  which  the  will  plays  in  the  same 
way  that  the  musician  plays  upon  the  piano.  Considerations  of 
various  kinds  have  given  to  the  cerebellum  a  preponderant  role  in 
the  elaboration  of  movements.  In  mammals,  even  those  at  the 
top  of  the  scale  (superior  apes),  the  hemiplegia,  which  follows  the 
ablation  of  the  motor  zone  of  the  cerebral  cortex,  is  only  transi- 
tory, and  the  animal  recovers  almost  completely  the  faculty  of 
executing  movements  with  his  paralyzed  limbs.  In  the  same  way 
the  section  of  the  two  pyramids  in  the  monkey  does  not  abolish 
the  faculty  of  executing  movements.  After  the  section  of  the 
crossing  of  the  pyramids  Rothmann  did  not  observe  any  symptoms 
of  spastic  paralysis,  only  a  certain  awkwardness  and  an  exaggera- 
tion of  reflexes,  which  persisted  two  or  three  weeks,  was  pro- 
duced. In  man,  the  resection  of  the  motor  zone,  practiced  for  the 
purpose  of  relieving  epilepsy,  is  often  only  followed  by  a  light 
hemiplegia  which  improves  with  time.  Often,  only  disturbances 
of  sensibility  and  incoordination  of  movements  are  observed. 

These  results  appear  to  be  in  contradiction  to  the  teachings 
of  pathology,  and  in  effect,  foci  of  cortical  softening  situated  in 
the  motor  zone  entail  permanent  paralyses,  which  are  accompanied 
by  very  severe  contractions  of  the  paralyzed  member.  This 
contradiction,  is  perhaps  only  apparent;  the  foci  of  softening 
are  rarely  limited  to  the  cortex  of  the  motor  zone,  and  always 
trench  more  or  less  upon  the  adjacent  white  substance  and  the 
neighboring  convolutions  and  are  not  in  any  way  comparable  to 
surgical  resections.  The  zone  of  the  cerebral  cortex  which  pro- 
jects itself  upon  the  cerebellum  through  the  intermediation  of 
the  cerebral  peduncles,  the  pontine  nuclei,  and  the  middle  cere- 
bellar  peduncle,  is  much  more  extended  than  the  cortical  motor 
zone  (ascending  frontal  convolution).  It  comprises,  among 
others,  the  ascending  parietal  and  the  second  and  third  temporal 
convolutions.  If  we  only  take  into  consideration  the  involvement 
that  these  two  types  of  lesions  (that  is,  surgical  resections  and 
foci  of  softening)  may  have  upon  the  anatomical  and  physiologi- 
cal relations  of  the  cerebrum  and  the  cerebellum,  we  cannot  put 
them  both  in  the  same  category. 


l6o  THE   FUNCTIONS   OF   THE   CEREBELLUM 

We  may  ask  in  fact,  what  organ  is  it  that  presides  over  the 
elaboration  and  execution  of  movements  since  the  motor  zone  of 
the  cerebrum  may  be  destroyed  without  abolishing  motility.  By 
reason  of  the  importance  of  its  development  and  its  anatomical 
relation  and  of  its  indisputable  role  in  the  physiology  of  move- 
ment, one  would  be  disposed  to  admit  that  this  organ  is  the  cere- 
bellum. It  is  more  probable  that  it  is  one  of  the  vicarious  organs 
which  may  supplement  the  excitable  zone  of  the  cerebral  cortex. 
The  disturbances  of  locomotion  are,  in  fact,  permanent  when  the 
cerebellum  and  the  excitable  zone  are  simultaneously  destroyed, 
but  we  cannot  range  ourselves  with  Adamkiewicz  and  make  the 
cerebellum  the  center  of  voluntary  acts  and  movements,  since, 
after  the  destruction  of  the  cerebellum  (both  in  animals  and  in 
man),  voluntary  movement  is  not  abolished,  but  only  modified. 

Horsley  has  returned  recently  to  this  question  in  connection 
with  a  very  interesting  case  of  resection  of  the  gyrus  precentralis 
(ascending  frontal),  in  an  individual  affected  with  Jacksonian 
epilepsy.  The  portion  of  the  gyrus  which  was  to  be  removed  was 
excited  by  bi-polar  faradic  currents,  and  it  was  posisble  to  ascer- 
tain that  the  excited  lesion  corresponded  to  the  center  for  the 
upper  limb.  After  the  operation  the  motility  of  the  limb  was, 
in  large  measure,  restored,  and  from  this  point  of  view  the  result 
was  quite  comparable  to  those  which  have  been  obtained  in  mon- 
keys. Horsley  recalls,  in  this  connection,  that  Rothmann  was 
able  to  obtain  isolated  movements  of  the  arm  by  electrical  excita- 
tion of  the  corresponding  center,  after  having  interrupted,  and 
consequently  put  out  of  consideration,  the  pyramidal  path.  He 
concludes  from  these  various  observations  that  voluntary  move- 
ments have  not  their  only  source  in  the  motor  zone  of  the  cere- 
bral cortex.  The  motor  function  would  also  be  put  into  play 
by  the  gyrus  post-centralis  (ascending  parietal)  which  is  a  center 
of  representation  of  the  limbs,  and  the  fibers  of  which  project 
themselves  through  the  thalamus  by  following  the  internal  cap- 
sule. One  might  suppose  that  after  the  disappearance  of  the 
peduncular  path,  the  restitution  of  the  motor  functions  was  made 
through  the  red  nucleus  and  the  rubro-spinal  bundle  of  Monakow. 
The  red  nucleus  does  receive,  in  fact,  fibers  from  the  thalamus 
and  from  the  cerebellum  (superior  cerebellar  peduncle).  For 


THE    CEREBELLUM    AND    MOTILITY  l6l 

these  reasons  we  cannot  accord  the  cerebello-rubro-spinal  path 
the  principal  part  in  substitution  for  the  cortical  motor  zone  in  the 
execution  of  voluntary  movements,  and  the  hypothesis  given  out 
by  Horsley,  that  of  the  substitution  by  means  of  the  parieto-thal- 
amo-rubro-spinal  path,  seems  at  present  the  more  acceptable. 
There  is  occasion,  however,  to  make  some  reservations  as  to  this 
interpretation.  It  is  applicable,  perhaps  in  the  case  of  man, 
whereas,  it  is  debatable  in  the  case  of  monkeys  and  other  mam- 
mals. In  fact  by  making  a  bi-lateral  section  of  the  lateral  col- 
umns of  the  spinal  cord,  that  is  to  say,  by  interrupting  at  the  same 
time  the  pyramidal  tract  and  the  bundle  of  Monakow,  Rothmann 
produced  in  the  monkey  only  a  slight  and  transitory  paresis  of  the 
extremities.  The  question,  therefore,  is  not  definitely  solved,  and 
besides,  the  respective  roles  of  the  various  centers  in  the  elabora- 
tion of  movements  is  far  from  being  definitely  elucidated,  and 
it  would  be  imprudent,  in  this  connection,  to  force  analogies  be- 
tween man  and  animals.  Nothing,  in  any  case,  authorizes  us  to 
look  upon  the  cerebellum  as  a  generating  center  for  voluntary 
movements. 

Hemiplegia,  or  rather  hemiparesis,  noticed  by  Pineles  and 
Mann  in  certain  individuals  afflicted  with  lesions  seated  in  the 
cerebellum  or  in  the  course  of  the  cerebellar  paths,  may  be  in- 
voked in  support  of  the  theory  at  present  under  discussion. 
Without  entering  into  the  details  of  these  observations  in  which 
it  is  mentioned,  we  may  remark  that  these  observations  concern 
principally  tumors,  or  at  any  rate  lesions  which  do  not  affect  ex- 
clusively the  cerebellar  paths.  When  these  lesions  are  located  in 
the  tegmentum  pontis,  and  cut  off,  either  partially  or  wholly, 
the  efferent  or  afferent  fibers  of  the  cerebellum,  it  is  rare  that  they 
do  not  trench  upon  other  fibers  of  the  tegmentum,  and  the  path- 
ological physiology  therefore  becomes  extremely  complex. 

On  the  other  hand,  hemiplegia  is  not  constant,  and  is  lacking 
in  observations  of  lesions  strictly  confined  to  the  cerebellum. 
Mann  explains  it  besides  as  cerebellar  ataxia,  due  to  the  suppres- 
sion of  the  peripheral  excitations  which  come  from  the  muscles. 
This  has,  as  a  consequence,  a  weakening  of  the  force  of  inner- 
vation. 


1 62  THE  FUNCTIONS  OF  THE  CEREBELLUM 

THE  CEREBELLUM  THE  CENTER  OF  COORDINATION 
AND  REGULATION 

Flourens  (1824-1842),  whose  numerous  experiments  on  the 
cerebellum  have  remained  justly  celebrated — these  experiments 
were  made  principally  upon  birds  but  also  upon  reptiles  and 
mammals — is  the  first  author  who  localized  the  faculty  of  coordi- 
nating and  regulating  movements  in  the  cerebellum. 

I  recall  firstly,  the  fundamental  results  of  his  experiments. 
In  removing  the  cerebellum  of  a  pigeon  by  successive  layers,  he 
noted  that  the  movements  became  at  first  brusque  and  ungoverned 
then,  gradually,  the  animal  lost  the  ability  to  jump,  to  fly,  to  walk, 
and  to  hold  itself  upright.  Equilibrium  was  abolished,  to  remain 
in  an  upright  position  the  animal  was  obliged  to  support  himself 
with  his  tail  and  his  wings.  The  gait  was  staggering  and  it  had 
the  air  of  a  drunken  animal. 

It  was  the  same  in  the  case  of  a  turkey  cock,  whose  staggering 
gait  resembled  that  of  a  drunken  man.  After  complete  destruc- 
tion, the  upright  position  and  walking  were  impossible.  A  dog, 
from  which  he  had  removed  the  cerebejlum  by  deeper  and  deeper 
resections,  lost  immediately  the  ability  to  move  with  order  and 
regularity.  The  gait  became  staggering;  he  drew  back  when  he 
wished  to  go  forwards.  His  efforts  to  feed  himself  were  very 
great  but  he  could  not  moderate  them.  He  threw  himself  for- 
ward with  impetuosity,  and  did  not  fail  to  fall  or  roll  over  him- 
self. He  could  not  seize  with  his  mouth  with  certainty  any  object 
which  was  presented  to  him. 

From  the  ensemble  of  these  experiments,  Flourens  draws  the 
following  conclusions : 

"  ist.  In  mammals  as  well  as  in  birds,  a  slight  alteration  in  the 
cerebellum  produces  a  slight  disharmony  in  the  movements.  This 
disharmony  grows  with  the  alteration,  and  finally,  the  total  loss 
of  the  cerebellum  engenders  the  total  loss  of  the  regulating  faculty 
of  movements. 

"  2nd.  Nevertheless,  there  is  in  this  regularity  and  this  exact 
repetition  of  phenomena,  a  curious  fact,  and  that  is  that  the  move- 
ments thus  disordered  by  reason  of  the  lesion  of  the  cerebellum, 
correspond  to  all  the  ordered  movements.  In  a 'bird  which  flies 
it  is  in  the  flight  that  the  disorder  appears ;  in  a  bird  which  runs, 
it  is  in  the  gait ;  and  in  a  bird  which  swims,  it  is  in  the  act  of 


THE    CEREBELLUM    AND    MOTILITY  163 

swimming.     There  is  a  swimming  and  a  flight  resembling  drunk- 
enness, just  as  there  is  a  gait. 

"  Along  with  the  loss  of  the  cerebellum  coinciding  constantly 
with  the  loss  of  the  locomotor  faculties,  the  intellectual  and  per- 
ceptive faculties  do  not  lose  their  integrity  in  any  way  and  on  the 
other  hand,  as  long  as  the  operation  does  not  pass  the  limits  of 
the  cerebellum,  there  is  no  sign  of  convulsions. 

"  The  faculty  productive  of  convulsions  or  muscular  contrac- 
tions, the  faculty  of  coordination  of  these  contractions,  and  the 
intellectual  and  perceptive  faculties,  are  three  orders  of  faculties 
essentially  distinct,  reposing  in  three  kinds  of  nervous  organs,  also 
essentially  distinct." 

Although  all  the  movements  of  locomotion  may  be  lost,  the 
movements  of  conservation  are  none  the  less  preserved. 

One  cannot  express  more  positively  the  coordinating  and  reg- 
ulating action  of  the' cerebellum  in  all  movements  and  in  the  main- 
tenance of  equilibrium. 

The  coordinating  action  of  the  cerebellum  has  been  variously 
defined  by  physiologists.  Schiff  criticizes  the  theory  of  Flourens. 
It  is  not  the  irregular  succession  of  movements  that  is  observed 
after  a  cerebellar  lesion.  It  is  an  alteration  of  the  form  and  the 
direction  of  the  movements;  but  the  general  direction  oi  the 
movements  is  preserved.  The  head  is  raised  when  the  animal 
wishes  to  raise  himself  upon  his  paws;  it  is  lowered  when  he 
wishes  to  run  away.  SchifF  recognizes  nevertheless  that  all  these 
movements  are  disturbed,  that  there  are  oscillations  and  waver- 
ings, but  the  animal  reacts  in  an  appropriate  manner  to  these 
oscillations  and  to  this  wavering.  To  verify  the  conservation  of 
coordination  he  placed  a  squirrel  which  had  been  deprived  of  its 
cerebellum  upon  a  sounding  board;  it  was  easy  to  observe  that 
the  rhythm  of  the  gallop  was  preserved.  The  succession  was  not 
altered,  but  the  isolated  sounds  which  made  up  the  principal 
tempo  had  become  unequal  in  intensity  and  duration,  etc. 

The  reason  for  the  oscillation  of  the  head  is  not  to  be  sought, 
according  to  Schiff,  in  an  insufficient  muscular  contraction,  which 
allows  the  weight  or  the  elasticity  of  the  antagonistic  muscles  to 
act,  but  in  a  too  intense  nervous  impulse  to  the  antagonistic  mus- 
cles at  the  same  time.  This  is  why  when  the  animal  seeks  to 
take  a  piece  of  meat  which  it  sees  upon  the  ground,  one  can  feel 


164  THE   FUNCTIONS   OF   THE   CEREBELLUM 

by  palpation  of  the  back  of  the  neck,  slight  intercurrent  contrac- 
tions of  the  elevator  muscles  of  the  head.  These  contractions 
are  provoked  every  time  that  the  head  attempts  to  take  or  pre- 
serve an  attitude.  If  the  animal  is  lying  down  or  if  he  wishes 
to  sleep  all  these  contractions  disappear.  The  same  phenomenon 
can  be  observed  in  the  fixator  muscles  of  the  dorsal  column,  and 
of  the  lumbar  column  when  the  animal  wishes  to  sit  up  upon 
his  hind  paws. 

In  conclusion,  there  are  aberrations  of  the  motor  innervation, 
which  act,  not  only  upon  the  muscles  whose  contraction  is  neces- 
sary, but  also  upon  the  antagonists  and  the  neighboring  muscles. 

The  action  of  the  cerebellum  would  thus  not  be  a  braking 
action,  such  as  one  arresting  certain  irradiations  of  the  motor 
innervation;  this  action  would  rather  be  concentrated  entirely  in 
a  determinate  impulse.  In  such  a  hypothesis  a  bilateral  lesion  of 
the  cerebellum  would  entail  alterations  of  movements  twice  as 
intense,  whereas  Schiff  insists  upon  the  fact  already  brought  to 
light  by  Vulpian  that  the  disturbances  of  coordination  are  much 
less  marked  after  absolutely  symmetrical  lesions  of  the  cerebellum. 

The  conclusion  of  Schiff  is  that  in  the  cerebellum  the  appa- 
ratus is  located  which  puts  into  play  groups  of  muscles  necessary 
for  the  accomplishment  of  a  complicated  movement.  Not  only 
groups  of  muscles  which  direct  the  wished  for  movement,  but 
also  other  groups  of  muscles  which  only  fix  the  limb  and  the 
joints,  and  which  thus  prepare  fulcrums  for  the  levers  and  whose 
feeble  contractions  are  antagonistic  to  the  movements  of  the  whole. 

If  paralysis  and  feebleness  of  movements  are  not  the  conse- 
quence of  cerebellar  lesions,  it  is,  nevertheless,  necessary  to  admit 
that  from  the  beginning  movements  are  not  made  with  their 
normal  force,  the  slowness  of  the  movements  proves  this.  Schiff 
admits  that  he  is  entirely  unable  to  explain  the  mechanism  of  this 
seeming  reinforcement  of  movements. 

There  are,  in  the  views  of  Schiff,  upon  the  functions  of  the 
cerebellum,  some  very  ingenious  ideas  and  some  hypotheses  which 
are  at  first  sight  extremely  seductive.  They  are  not,  however, 
beyond  discussion.  If  coordination  is  disturbed  it  is  not  in  as  far 
as  concerns  the  direction  of  the  movement  which  is  preserved. 
The  majority  of  the  authors,  both  physiologists  and  clinicians  are 
unanimous  upon  this  point.  Once  more,  the  motor  disturbances 


THE    CEREBELLUM    AND    MOTILITY  165 

of  cerebellar  patients  differ  from  peripheral  ataxia  by  the  preser- 
vation of  the  direction  of  the  movement  and  by  the  practically 
negligible  influence  of  the  suppression  of  sight.  On  the  contrary 
— both  experiments  and  clinical  observation  have  shown  it — the 
measure  of  the  movement  is  altered.  Luciani  admits,  with  some 
reserves,  that  dysmetria  exists.  The  same  with  Munk.  The 
squirrels  of  Schiff  appear  also  to  execute  movements  of  unequal 
force,  lacking  measure.  A  dog  in  which  the  cerebellum  has  been 
destroyed  raises  his  paws  higher  than  normal.  When  the  destruc- 
tion has  been  in  one  hemisphere  only,  only  the  paws  of  the 
same  side  are  raised  too  high  and  replaced  too  forcibly.  The 
same  thing  happens  with  a  cat  (Andre-Thomas).  Lewandow- 
sky  mentions  unmeasured  movements  of  the  fore  paw  when  the 
animal  tries  to  seize  a  bone.  The  clinicians  have  noted  a  number 
of  times  movements  of  too  sudden  a  nature  in  the  course  of  cere- 
bellar atrophies  (Dejerine  and  Andre-Thomas).  Babinski  has 
observed  unmeasured  movements  in  patients  "  in  whom  the  cere- 
bellar apparatus  "  was  in  question.  I  myself  with  Jumentie  have 
insisted  upon  the  presence  of  dysmetria  when  the  movements  were 
too  rapidly  executed,  and  this  is  probably  the  reason  why  the 
movements  of  cerebellar  patients  are  usually  slow.  They  have  a 
feeling  of  their  awkwardness  in  the  too  prompt  execution  of 
movements. 

In  the  execution  of  a  movement  there  is  nothing  but  dys- 
metria. Whether  it  is  a  question  of  movements  or  attitudes  of 
the  head,  of  a  limb,  or  of  the  body  in  cerebellar  patients,  or  in  an 
animal  upon  whose  cerebellum  there  has  been  an  operation  (above 
all,  the  monkey),  these  movements  differ  from  normal  move- 
ments by  oscillations  or  tremor.  The  tremor  does  not  exist  in 
the  state  of  complete  relaxation  of  the  muscles.  It  is  produced 
in  two  conditions:  during  the  execution  of  the  movement,  and 
during  the  maintenance  or  beginning  of  an  attitude  (see  page  — ). 

We  recall  that  this  tremor  may  receive  two  explanations :  ( i ) 
The  movement  is  too  sudden  and  unmeasured  and  the  patient  cor- 
rects it  by  the  antagonistic  muscles;  this  explanation  has  been 
previously  refuted  by  me.  This  is  a  hypothesis  similar  to  the 
one  proposed  by  Schiff,  with  this  difference,  that  according  to  him 
intervention  of  the  antagonistic  muscles  is  not  voluntary  but  con- 
secutive to  an  aberration  of  the  motor  innervation.  This  does  not 


1 66  THE    FUNCTIONS   OF   THE   CEREBELLUM 

appear  to  us  to  be  any  better  founded.  If  when  the  dog,  alluded 
to  by  Schiff,  seeks  to  seize  a  piece  of  meat  which  is  on  the  ground, 
one  can  feel  by  palpating  the  neck  slight  intercurrent  contractions 
of  the  elevating  muscles  of  the  head ;  it  is  not  proper  to  consider 
these  contractions  as  contractions  of  the  antagonistic  muscles,  for 
in  this  attitude  the  action  of  these  elevating  muscles  is  directly 
adapted  to  the  object  in  view.  Really,  during  the  lowering  of  the 
head  these  muscles  are  relaxed,  but  incompletely  so.  The  main- 
tenance and  variation  of  their  tonicity  are  essential  conditions 
for  the  accomplishment  of  these  movements  of  prehension. 

The  second  hypothesis  seems  to  me  to  conform  more  to  the 
facts,  as  I  have  already  said. 

(2)  Arrests  and  recontractions  are  produced  in  the  muscles. 
The  movement  instead  of  being  continuous  or  tonic  is  in  a  way 
epileptoid  or  clonic  (Andre-Thomas  and  Jumentie).  There  is, 
according  to  the  expression  of  Luciani,  a  defect  in  the  summation 
of  the  elementary  impulses.  The  cerebrum  supplies  the  place  of 
the  cerebellum,  but  to  a  measure  in  an  incomplete  manner,  and  it 
does  not  succeed  at  first  in  fusing  the  volitional  incitations  which 
preside  over  the  execution  of  the  movement,  or  the  maintenance 
of  the  attitude,  unless  the  movement  be  slow  and  watched  over. 
Stability,  nevertheless,  can  be  attained,  but  at  the  expense  of  a 
certain  time  and  it  is  preceded  by  a  period  of  attempts. 

Dysmetria  shows  in  its  turn  that  the  elementary  impulses  are 
"too  strong,  and  consequently  that  the  cerebellum  exercises  a  brak- 
ing influence  upon  the  totality  of  the  movements.  J.  Babinski 
expresses  a  similar  opinion.  But,  we  say  again,  this  influence  is 
manifested  in  moderating  the  elementary  impulse,  and  not  in 
causing  the  antagonistic  muscles  to  intervene. 

If  the  suppression  or  the  diminution  of  the  cerebellar  function 
is  followed  by  dysmetria  and  discontinuity  of  movement,  one 
must  admit  that  the  cerebellum  has  a  particular  tonic  influence 
which  has  for  its  object  the  regulating  of  the  movement  and  the 
assuring  of  its  execution  with  a  minimum  effort  and  a  perfect 
adaptation  to  the  object  in  view.  It  is  thus  that  we  must  look 
upon  the  tonic  action  of  the  cerebellum,  and  the  astasia  (i.  e.,  the 
oscillation  and  intention  tremor)  would  seem  only  to  be  a  conse- 
quence of  it.  In  reality  this  is  practically  the  same  idea  expressed 
by  Luciani  when  he  says  that  the  tonic  action  of  the  cerebellum 


THE   CEREBELLUM    AND    MOTILITY  1 67 

consists  in  increasing  the  duration  and  the  tension  of  the  muscles 
during  functional  pause.  The  action  of  the  cerebellum  is,  there- 
fore, at  the  same  time  inhibitory  or  braking,  and  excitor-motor  or 
tonic.  In  any  case,  the  disturbances  of  tone  of  cerebellar  origin 
should  not  be  confounded  with  the  hypotonus  of  tabetics,  which 
is  manifested  by  an  articular  relaxation. 

The  cerebellum  is  a  regulator,  but  it  is  not  only  a  regulator 
of  muscular  contractions;  according  to  Schiff  the  cerebellum  is 
the  seat  of  apparatus  which  puts  into  play  the  muscular  groups 
necessary  for  the  accomplishment  of  complicated  movements,  and 
as  such  it  plays  a  preponderant  role  in  equilibrium.  This  is,  in 
fact,  the  theory  of  asynergy  propounded  by  J.  Babinski,  which 
will  be  taken  up  again  a  little  further  on  in  relation  to  equilibra- 
tion. Munk  and  Probst  have  expressed  a  similar  opinion.  For 
them  the  cerebellum  is  a  regulating  apparatus  for  muscular  action, 
entering  into  play  in  the  maintenance  of  the  station  of  the  body, 
in  locomotion  and  in  voluntary  automatic  and  reflex  movements. 

According  to  the  observations  of  Horsley,  the  activity  of  the 
nerve  centers  is  translated  by  a  combination  of  clonus  and  tonus, 
and  the  motor  manifestations  differ  according  to  the  proportions 
of  one  or  the  other.  Clonism  is  a  property  of  excitation  from  the 
cerebral  cortex  and  tonism  of  the  subjacent  centers.  The  con- 
clusions of  Horsley  and  Bouche  are  very  easily  demonstrable  on 
this  point.  They  injected  essence  of  absinth  into  the  jugular  vein 
of  .a  cat  three  weeks  after  the  ablation  of  the  left  cerebral  hemi- 
sphere. On  the  left  side  a  tonico-clonic  access  of  contractions 
was  produced  with  the  limbs  in  flexion,  on  the  right  side  a  tonic 
access,  principally  in  extension.  During  the  course  of  an  access, 
the  authors  made  an  instantaneous  section  of  the  mesencephalon : 
immediately  the  clonic  movements  were  changed  into  tonic  ones 
in  the  whole  body,  the  head  was  drawn  backwards  and  the  limbs 
of  the  left  side  were  in  extension.  Excitations  of  the  inferior 
centers,  among  which  is  counted  the  cerebellum,  gave  rise  to  ex- 
clusively tonic  attacks.  Some  clinical  facts  also  sustain  this 
observation.  I  will  cite  among  others  the  following  observation 
of  Jackson.  It  concerns  a  child  afflicted  with  a  tumor  of  the 
median  lobe  of  the  cerebellum  as  large  as  a  billiard  ball.  The 
gait  was  staggering,  the  legs  executed  excessive  movements  and 
were  stiff  and  in  extension  along  the  prolongation  of  the  body. 


1 68  THE   FUNCTIONS   OF   THE   CEREBELLUM 

The  feet  were  in  hyperextension,  slightly  inclined  inward.  Occa- 
sionally tetanoid  convulsive  attitudes  were  observed.  This  is  how 
they  were  produced  according  to  Mackenzie  who  observed  them : 
The  forearms  were  flexed  upon  the  arms,  the  arms  were  held 
close  to  the  sides,  the  head  drawn  backwards,  with  an  incurvation 
of  the  back,  the  legs  stretched  out,  also  incurved.  The  patient 
passed  urine  sometimes  during  these  crises.  During  the  crisis 
the  attitude  was  the  caricature  of  a  man  or  a  child  running  very 
rapidly.  Jackson  concludes  from  this  that  in  convulsions  of  cere- 
bellar  origin  the  spasm  is  tonic,  whereas  in  cerebral  convulsions 
it  is  principally  clonic.  The  convulsions  affected  more  the  bilat- 
eral muscles  of  the  legs  and  trunk,  whereas  in  cerebral  affections 
the  muscles  of  one  side  are  more  affected,  and  those  of  the  arm 
more  than  those  of  the  leg.  These  crises  resemble  tetanus  more 
than  epilepsy.  In  conclusion,  according  to  Jackson,  the  cerebel- 
lum coordinates  more  particularly  those  movements  which  serve 
the  purpose  of  locomotion  and  other  quasi-automatic  acts,  whereas 
the  cerebrum  coordinates  more  particularly  those  movements 
which  serve  for  voluntary  acts. 

This  opposition  established  by  Jackson  between  the  clonic 
character  of  the  cerebral  convulsions  and  the  tonic  character  of 
those  of  cerebellar  origin,  is  to  be  compared  with  the  special  form 
that  movement  takes  in  individuals  affected  with  cerebellar 
atrophy.  It  becomes  discontinuous  and  clonic,  apparently  on 
account  of  the  disappearance  of  the  tonic  cerebellar  influx. 

THE  CEREBELLUM  AND  REFLEX  MOVEMENTS 

In  animals  which  are  deprived  of  half  of  the  cerebellum  the 
tendon  reflexes  without  being  spasmodic  are  exaggerated  on  the 
side  of  the  destruction  (Russell  and  Andre-Thomas).  In  the 
same  way  an  exaggeration  of  the  reflexes  is  noted  in  man  in 
most  of  the  cases  of  primary  atrophy  of  the  cerebellum.  It  seems, 
therefore,  that  under  the  influence  of  the  functional  suppression 
of  the  cerebellum  there  would  be  in  the  reflex  movements,  as  in 
the  voluntary  and  automatic  movements,  a  defect  of  measure. 
One  may  allow  to  the  cerebellum  a  general  braking  influence, 
exercised  over  all  movements.  Patrizi  has  controlled  this  fact  by 
the  graphic  method,  the  reflex  is  prompter,  and  the  excursion  of 
the  member  is  greater  on  the  side  of  the  hemi-destruction. 


THE  CEREBELLUM  AND  MOTILITY  169 

THE  CEREBELLUM,  EQUILIBRATION  AND  SYNERGY 

It  is  incontestable  that  dysmetria  and  discontinuity  of  move- 
ment contribute  to  disturb  equilibration.  The  disturbances  of 
equilibration,  however,  appear  to  consist  of  more  complicated 
disorders. 

The  loss  of  equilibrium  was  noted  by  Flourens  in  the  animals 
from  which  he  removed  the  cerebellum  in  successive  layers.  Ac- 
cording to  Bouillaud,  an  animal  deprived  of  its  cerebellum  is  not 
paralyzed.  What  it  lacks  is  coordination  of  the  movements  of 
walking  and  of  standing.  On  the  other  hand,  the  simple  move- 
ments of  the  head,  of  the  trunk  and  of  the  limbs  can  be  per- 
formed. Bouillaud  admits  that  there  exists  in  the  cerebellum  a 
force  which  presides  over  the  association  of  the  movements  of 
which  the  divers  acts  of  locomotion  are  composed. 

The  experiments  of  Ferrier  upon  the  functions  of  the  cere- 
bellum have  been  previously  related  at  length.  Some  reserva- 
tions were  made  as  to  the  value  of  the  results  from  electrical  exci- 
tations, because  those  authors  who  have  repeated  them  did  not 
obtain  concordant  results ;  the  excitability  of  the  cerebellum  is  still 
a  question  to  be  studied.  Ferrier  looks  upon  the  cerebellum  as 
a  complex  arrangement  of  centers  individually  differentiated, 
which,  acting  together,  regulate  the  divers  muscular  adaptations 
necessary  for  the  maintenance  of  equilibrium.  Comparing  the 
effects  of  excitations  with  the  symptoms  observed  in  the  course 
of  disease,  or  in  experimental  lesions  of  the  cerebellum  with  those 
which  have  been  described  by  Purkinje  and  Hitzig,  as  when  one 
causes  a  galvanic  current  of  moderate  strength  to  flow  through 
the  head,  with  the  vertiginous  sensation  produced  by  rotation 
around  the  longitudinal  axis,  and  the  secondary  compensatory 
reactions,  Ferrier  deduces  that  the  right  side  of  the  cerebellum 
coordinates  the  muscular  mechanism  which  prevents  a  displace- 
ment of  equilibrium  to  the  opposite  side;  in  the  same  way  the 
movement  backward  of  the  head,  the  extension  of  the  trunk,  and 
the  limb,  and  the  elevation  of  the  eyes,  determined  by  an  irrita- 
tion of  the  anterior  part  of  the  median  lobe,  are  the  compen- 
satory efforts  to  counterbalance  rotation  forward. 

"  The  cerebellum  would  apear  to  be,  therefore,  a  complex 
arrangement  of  centers  individually  differentiated,  which,  acting 
together,  regulate  the  various  muscular  adaptations  necessary  for 


THE   FUNCTIONS    OF   THE   CEREBELLUM 

the  maintenance  of  equilibrium ;  every  tendency  to  a  displace- 
ment of  equilibrium  around  a  vertical,  horizontal  or  intermediary 
axis,  acting  as  an  excitant  for  the  particular  center  which  calls 
into  play  the  compensatory  or  antagonistic  action." 

The  cerebellum  is  developed  proportionally  to  the  variety  and 
complexity  of  the  muscular  activities.  Lesions  of  the  cerebellum 
do  not  cause  paralysis  of  voluntary  movements.  If  fatigue  super- 
venes rapidly  in  animals  upon  whom  a  cerebellar  lesion  has  been 
made,  it  is  as  a  result  of  the  efforts  which  they  are  obliged  to 
make  to  replace  a  mechanism  independent  of  consciousness,  and 
not  because  the  cerebellum  is  a  source  of  energy,  that  this  takes 
place. 

In  his  later  researches,  made  in  collaboration  with  Turner, 
Ferrier  is  less  categorical,  and  he  recognizes  that  the  problem  of 
the  function  of  the  cerebellum  is  not  nearly  solved. 

I  have  insisted  in  my  thesis  upon  the  importance  of  the  dis- 
turbances of  equilibrium  in  animals  deprived  partially  or  wholly 
of  the  cerebellum.  When  an  animal  has  been  deprived  of  half  its 
cerebellum,  no  matter  what  attitude  it  wishes  to  take,  or  what 
movement  it  wishes  to  execute,  it  is  drawn  towards  the  side  of  the 
lesion,  and  falls  towards  that  side.  The  first  days  after  the  opera- 
tion it  executes  movements  of  rolling  about  a  longitudinal  axis, 
from  the  uninjured  towards  the  injured  side.  In  repose  it  lies 
upon  the  injured  side  and  in  the  prone  position  the  head  is 
deviated  toward  that  side.  Later,  when  it  makes  its  first  attempts 
to  walk,  it  is  drawn  in  spite  of  itself  by  a  movement  of  lateral 
translation  to  the  operated  side  and  falls  in  that  direction.  The 
rotation  about  the  longitudinal  axis,  the  decubitus  upon  the  side 
of  the  lesion,  the  fall,  and  the  movement  of  translation,  are  but 
the  same  phenomena  in  different  degrees.  I  have  explained  a 
few  pages  back  the  nature  of  these  phenomena  and  I  have 
rejected  the  theory  proposed  by  Luciani,  who  makes  them  irrita- 
tive phenomena.  For  me  they  show,  on  the  contrary,  the  loss 
of  the  totality  of  those  reactions  which  prevent  the  displacement 
of  the  center  of  gravity  towards  the  side  of  the  lesion,  and  conse- 
quently a  disturbance  of  equilibrium. 

While  standing  upon  the  four  paws,  one  can  admit  that  in  a 
normal  animal  equilibrium  is  preserved  because  the  tonicity  of 
the  muscles  of  the  head  and  the  vertebral  column  are  equal  on 


THE    CEREBELLUM    AND    MOTILITY  I /I 

both  sides.  Suppose  that  the  actions  of  the  muscles  of  one  side 
are  lacking  or  are  weaker?  That  of  the  muscles  of  the  opposite 
side,  continuing  to  act  alone,  will  determine  a  movement  of  tor- 
sion about  the  longitudinal  axis,  that  is  to  say,  a  movement  of 
rotation. 

When,  during  walking,  a  fore  paw  is  lifted  from  the  ground, 
equilibrium  is  compromised,  and  the  body  tends  to  sink  down  on 
the  same  side  if  a  modification  of  tonus  in  certain  muscular 
groups  is  not  produced.  A  modification  which  is  only  a  force  of 
reaction  consisting  of,  in  this  type  of  animal,  a  movement  of 
torsion  of  the  neck  and  the  anterior  portion  of  the  body,  about  the 
longitudinal  axis,  associated  with  an  inclination  of  the  head  in  the 
opposite  direction,  or,  if  one  prefers,  in  an  augmentation  of  the 
tonicity  of  the  corresponding  muscles.  In  an  animal  deprived  of 
the  cerebellum  this  reaction  is  lacking,  this  is  why  the  animal 
falls  on  the  same  side  as  the  destroyed  hemisphere.  The  fall  is 
all  the  more  brusque  as  the  contra-lateral  force  of  reaction  con- 
tinues to  act.  This  is  why  according  to  the  judicial  observations 
of  Schiff  and  Vulpian  equilibrium  seems  to  be  more  profoundly 
disturbed  after  the  destruction  of  half  of  the  cerebellum  than 
after  the  destruction  of  the  whole  of  it. 

What  is  true  for  the  lifting  of  the  fore  paw  is  equally  So  for 
the  lifting  of  the  hind  paw. 

Whether  the  destruction  of  the  cerebellum  has  been  unilateral 
or  total,  these  phenomena  amend  progressively  and  the  animal 
succeeds  successively  in  standing  up,  in  walking,  and,  eventually, 
in  running.  The  cerebellum  is  supplied  by  other  centers  and 
more  by  the  cerebrum  than  by  all  the  others.  Equilibrium,  instead 
of  being  spontaneous  and  automatic,  becomes  in  a  manner  a  thing 
intentional  or  willed.  The  body  has  no  longer  the  suppleness  it 
had  before  the  operation  and  is  as  if  ankylosed.  The  head  is  stiff 
and  fixed.  The  paws  are  not  lifted  with  the  same  regularity  and 
at  the  proper  time.  The  limbs  are  lifted  suddenly  and  replaced 
in  the  same  manner.  These  disorders  reappear  or  increase  when 
the  animal  progresses  on  an  inclined  plane.  During  the  ascent 
of  a  stairway  the  head  and  the  trunk  are  placed  in  exaggerated 
hyperextension,  and  at  the  moment  of  projecting  its  paws  for- 
ward the  animal  falls  backward.  It  is  no  longer  capable  of  asso- 
ciating the  movements  of  the  head  and  the  body  with  those  of 


172  THE   FUNCTIONS   OF   THE    CEREBELLUM 

the  limbs;  or  either  it  does  it  too  suddenly  and  equilibrium  is 
broken.  Recently  Hulshoff  Poe  insisted  upon  the  differences  be- 
tween the  jump  of  a  normal  dog  and  that  of  a  dog  deprived  of 
its  cerebellum.  In  the  first,  at  a  certain  moment,  the  two  hind 
paws  are  drawn  simultaneously  to  the  body;  the  dog  deprived  of 
the  cerebellum,  after  the  period  of  asthenia  has  passed,  can  also 
jump,  but  his  two  hind  paws  take  dissimilar  attitudes,  instead  of 
being  placed  simultaneously  in  a  symmetrical  position  as  in  the 
normal  dog. 

An  individual  affected  with  cerebellar  atrophy  conducts  him- 
self in  the  same  manner.  When  he  descends  a  stairway,  the 
body  does  not  follow  the  movement  of  the  legs,  and  he  often 
risks  falling  backward.  In  the  same  way  as  in  the  dog  the  move- 
ments of  the  posterior  and  anterior  paws  do  not  associate  them- 
selves together  regularly,  so  in  man  during  walking,  the  movements 
of  the  arms  do  not  associate  themselves  with  those  of  the  legs 
and  the  body.  When  a  cerebellar  patient  places  his  foot  upon  a 
chair,  or  simply  lifts  it  from  the  ground,  he  does  not  any  longer 
execute  the  necessary  compensating  movements  for  the  main- 
tenance of  equilibrium  broken  by  the  displacement  of  the  center 
of  gravity.  Besides,  is  he  not  conscious  of  this  defect  of  equi- 
librium and  stability,  which  manifests  itself  at  the  least  change  of 
attitude,  or  the  least  displacement  of  the  center  of  gravity? 

Schiff  is  right  when  he  says  that  the  cerebellum  is  the  center 
of  an  apparatus  which  puts  into  play  the  necessary  group  of  mus- 
cles for  the  accomplishment  of  a  complicated  movement.  Ferrier 
is  also  right  when  he  maintains  that  the  cerebellum  regulates  the 
various  muscular  adaptations  necessary  for  the  maintenance  of 
equilibrium. 

Luciani  has  vigorously  combated  this  theory ;  the  preservation 
of  the  power  of  swimming  in  animals  deprived  of  their  cerebel- 
lum and  the  efficiency  of  the  compensatory  acts  -by  means  of 
which  they  seek  to  avoid  a  fall  show,  on  the  contrary,  according 
to  him,  that  the  sense  of  equilibrium  functions  normally. 

These  two  arguments  are  weak.  Is  it  not  evident  that  the 
conditions  of  equilibration  are  very  different  in  the  water  than 
upon  the  ground,  and  that  in  the  first  situation  they  are  much 
more  easily  realized?  As  to  the  efficiency  of  these  compensatory 
acts,  it  merely  proves  that  the  faculty  of  equilibration  can  be  re- 


THE    CEREBELLUM    AND    MOTILITY  173 

gained  in  part,  thanks  to  the  intervention  of  other  centers  than 
the  cerebellum,  and  particularly  to  that  of  the  cerebrum. 

The  theory  of  asynergy,  set  forth  by  M.  Babinski,  after  an 
examination  of  patients  with  diseases  of  the  cerebellum,  or  of 
the  cerebellar  paths,  but  in  whom  the  cerebellum  does  not  always 
appear  to  be  the  only  organ  in  question,  hardly  differs  from  the 
theory  of  Schiff,  of  Ferrier,  and  of  the  one  which  I  have  myself 
maintained.  Since  asynergy  is  nothing  but  a  disturbance  of  mus- 
cular association,  the  impossibility,  or  the  difficulty  of  associating 
simple  movements  which  combine  for  the  execution  of  a  compli- 
cated movement,  it  does  not  differ  because  asynergy,  such  as  is 
understood  by  M.  Babinski,  is  a  more  general  fact,  and  includes 
all  muscular  association,  and  because  it  does  not  consider  any- 
thing but  the  association  of  movements.  In  the  theory  which  I 
have  formerly  maintained,  I  had  particularly  in  view  the  muscular 
reactions  adapted  to  the  maintenance  of  equilibrium.  The  ani- 
mals deprived  of  the  cerebellum,  the  patients  afflicted  with  cere- 
bellar atrophy,  have  in  effect  lost  the  rhythm  and  harmony  of  the 
movements  as  a  whole,  whether  it  is  a  question  of  walking,  run- 
ning, ascending  a  stairway,  or  jumping.  It  is  to  be  noted  like- 
wise that  in  the  majority  of  the  tests  that  M.  Babinski  has  in- 
vented to  show  asynergy,  it  is  a  question  of  association  of  move- 
ments during  which  the  equilibrium  of  the  body  is  in  considera- 
tion, but  in  some  of  them,  nevertheless,  asynergy  exists  in  the 
execution  of  movements  or  acts  which  do  not  compromise 
equilibrium. 

One  can  only  ask  if  sometimes  the  patient  does  not  volun- 
tarily intervene  in  the  decomposition  of  the  movement,  because 
he  is  conscious  of  the  awkwardness  produced  by  dysmetria.  In 
any  case,  the  tests  invented  by  M.  Babinski  should  be  repeated 
with  other  patients,  and  more  particularly  with  patients  afflicted 
by  destructive  lesions  strictly  localized  in  the  cerebellum.  It  is 
only  in  such  patients  that  one  can  appreciate  their  physiological 
value. 

With  Luciani,  Munk  recognizes  that  the  cerebellum  plays  a 
role  of  motor  reinforcement  which  it  exercises  upon  the  spinal 
muscle  centers.  This  function  is  in  no  way  peculiar  to  the  cere- 
bellum, it  shares  it  with  the  cerebrum.  (Luciani  also  thinks  that 
the  very  complex  physiological  activity  of  the  cerebellum  is  not 


THE   FUNCTIONS   OF   THE   CEREBELLUM 

a  specific  activity,  sui  generis,  but  rather  a  common  activity,  or 
so  to  say,  a  fundamental  activity,  of  the  whole  nervous  system.) 
The  true  specific  function  of  the  cerebellum  would  be,  according 
to  Munk,  the  static  function,  which  has  already  been  admitted 
by  Luciani. 

In  an  animal  in  which  the  cerebellum  has  been  destroyed,  it 
is  above  all  the  fine  and  delicate  equilibrium  which  disappears,  it 
can  no  longer  take  a  dangerous  position,  or  at  least  it  takes  it 
with  great  difficulty,  but  when  taken  it  can  preserve  it,  thanks  to 
a  coarser  faculty  of  equilibration  assured  by  other  nerve  centers. 
Munk  inquires,  nevertheless,  if  in  destroying  the  cerebellum  he 
really  removes  a  center  of  delicate  equilibrium,  or  if  he  does  not 
only  disturb  motility  and  the  sensibility  necessary  for  the  realiza- 
tion of  this  delicate  equilibrium ;  but  he  adopts  the  first  hypothesis 
because  the  animals  are  still  able  to  execute,  normally  a  large 
number  of  movements :  licking,,  to  wagging  the  tail ;  the  monkey 
can  eat  from  its  hand,  lick  its  paw,  catch  flies,  etc. 

The  differences  which  exist  between  the  normal  and  the  cere- 
bellar  gaits  do  not  depend,  according  to  Munk,  upon  a  disturb- 
ance affecting  the  execution  of  movements  of  the  extremities 
adapted  to  walking.  From  the  second  week  after  the  operation 
the  dog,  whether  he  is  lying  upon  his  side  or  lifted  by  the  skin 
of  his  back,  executes  irr  the  air  the  normal  movements  of  walking 
with  his  extremities.  A  monkey  climbs  with  normal  movements. 
Consequently,  according  to  Munk,  if  these  animals  are  not  able 
to  walk  normally,  it  is  because  they  have  been  deprived  of  the 
power  of  maintaining  their  equilibrium  by  the  aid  of  the  muscles 
of  the  vertebral  column  and  the  extremities.  This  deprivation 
concerns  the  maintenance  of  equilibrium  which  is  allied  in  the 
normal  movement  of  walking  to  these  normal  movements  of  the 
extremities.  After  the  operation  the  animal  tries  to  walk  as 
before,  but  as  he  fails  to  do  so,  he  adopts  a  new  method,  which 
is  the  jumping  gait.  This  is  a  functional  compensation.  The 
thing  that  proves  this  is  that  the  monkey  walks  normally  when  he 
is  leaning  against  a  wall  and  does  not  take  to  the  jumping  gait 
until  he  leaves  the  wall. 

The  isolated  movements  of  the  limbs,  however,  are  not  so 
intact  as  he  at  first  affirmed;  since  Munk  admits  the  existence  of 
dysmetria,  for  him  this  is  the  necessary  consequence  of  the  dimi- 


THE   CEREBELLUM    AND    MOTILITY  175 

nution  of  the  excitability  of  the  muscular  and  spinal  centers  of 
the  coordinated  movements.  When  it  is  necessary  to  change  the 
elevation  of  an  extremity  to  a  depression,  flexion  to  an  extension, 
abduction  to  adduction,  the  diminution  of  excitability  retards  the 
second  movement  or  even  inhibits  it,  and  the  first  movement  ex- 
ceeds the  normal;  it  is  thus  that  it  is  necessary  to  explain  the 
diminution  of  the  strength  of  the  operated  side,  and  the  awkward- 
ness of  prehension. 

Munk  does  not  accept  the  disturbances  of  cutaneous  sensi- 
bility observed  by  Russell  and  Lewandowsky.  On  the  other  hand, 
he  maintains  that  deep  sensation  is  affected :  "  Sensory  excitations 
which  originate  in  the  muscles,  in  the  articulations  and  in  the 
bones,  a  part  of  which  normally  go  to  the  cerebrum  in  passing 
through  the  cerebellum,  are  lost  when  the  cerebellum  is  de- 
stroyed." He  concludes  also  that  there  exists  a  cerebellar  tonus 
limited  to  the  vertebral  column  and  to  the  extremities,  and  which 
takes  its  source  exclusively  in  deep  sensation,  but  that  this  func- 
tion is  common  both  to  the  cerebellum  and  to  other  nerve  centers. 
Its  specific  function,  repeats  Munk,  is  the  delicate  maintenance 
of  equilibrium,  or  its  regulation;  in  the  seated  or  lying  position, 
in  walking  and  in  standing  up. 

The  theory  of  Munk  approaches  closely  to  the  theories  pro- 
pounded before  upon  the  role  of  the  cerebellum  in  equilibration. 
It  differs  from  them  by  its  complexity.  The  disturbances  of  deep 
sensibility  are  open  to  dispute.  This  explanation  of  dysmetria 
conforms  very  little  to  the  actual  reality.  Nevertheless,  the 
works  of  Munk  have  served  to  throw  light  upon  the  role  which 
the  cerebellum  plays  in  the  maintenance,  and  particularly  in  the 
reestablishment  of  equilibrium.  All  the  same  he  has  justly  brought 
out  the  fact  that  the  function  of  the  cerebellum  as  a  center  of 
reenforcement  is  by  no  means  specific. 

As  I  have  already  formerly  explained,  in  an  animal  in  which 
the  cerebellum  has  been  destroyed,  every  complicated  movement 
and  every  attitude  necessitates  a  sum  of  efforts  much  more  con- 
siderable than  in  a  normal  animal.  Before  he  is  able  to  reacquire 
or  to  find  the  mechanism  which  permits  him  to  reestablish  his 
equilibrium,  the  dog  which  has  been  operated  upon  must,  so  to 
speak,  test  his  muscles,  and  from  this  arises  the  cause  of  fatigue 
and  of  atony  in  the  sense  that  Luciani  has  given  it.  Each  cere- 


1/6  THE   FUNCTIONS   OF   THE   CEREBELLUM 

bellar  hemisphere  is  certainly  a  source  of  energy  for  the  corre- 
sponding side  of  the  body.  But  this  energy  has  a  special  use:  it 
\s  principally  adapted  to  the  reestablishment  of  equilibrium  or  of 
stability  in  all  of  the  attitudes  and  all  of  the  movements  of  the 
body.  When  the  cerebellar  function  has  just  disappeared  equi- 
librium is  not  on  that  account  definitely  lost,  because  it  can  be 
in  large  part  reacquired,  but  it  is  then  an  equilibrium  or  a  sta- 
bility less  perfectly  and  less  rapidly  obtained.  The  oscillations, 
at  times  very  strong  at  the  beginning  of  the  movement,  can  after- 
wards become  much  slighter  and  even  disappear. 

This  is  the  distinction  between  fine  equilibrium  and  coarse 
equilibrium  proposed  by  Munk.  The  cerebellum  looked  upon 
thus  is  an  organ  of  perfecting,  and  as  such  it  spares  this  task  from 
the  cerebral  activity  and  permits  it  to  spend  itself  otherwise. 

M.  Babinski  establishes  a  distinction  between  kinetic,  voli- 
tional equilibrium  which  would  be  disturbed  in  cerebellar  patients, 
and  static  equilibrium  which  would  be  preserved  or  even  exalted. 
To  the  support  of  this  opinion  he  invokes  catalepsy,  which  he  has 
observed  in  some  patients  affected  with  cerebello-pontine  lesions, 
and  which  has  been  noted  by  Rossi  in  a  case  of  parenchymatous 
atrophy  of  the  cerebellum.  Experimentation  and  clinical  obser- 
vation show  in  effect  that  static  equilibrium  is  less  disturbed  than 
kinetic  equilibrium,  and  that  immobility  is  easier  to  obtain  in  those 
movements  which  do  not  modify  the  conditions  of  equilibrium  of 
the  body.  Animals  deprived  of  the  cerebellum  have,  besides,  a 
tendency  to  inertia.  In  young  animals  when  the  sight  is  sup- 
pressed, there  is  a  complete  inertia  of  volition;  the  limbs  remain 
in  any  position  that  is  given  them,  on  the  condition  that  it  does 
not  provoke  a  painful  reaction  and  that  they  are  not  in  opposition 
to  the  laws  of  gravity  (Borgherini  and  Gallerani). 

I  observed  a  dog  deprived  of  his  cerebellum  who  later  became 
blind,  which  found  itself  in  the  same  condition;  it  kept  any  posi- 
tion that  was  given  it;  it  seemed  indifferent  to  everything  that 
happened  around  it,  and  scarcely  reacted  even  to  painful  excita- 
tions. It  did  not  bark,  and  was  in  a  very  marked  somniform  state 

(Fig.  SO- 

The  same  tendency  to  keep  the  attitudes  of  the  limbs  which 
were  given  to  them  has  been  noted  in  some  patients  affected  with 
abscesafor  tumor  of  the  cerebellum,  but  these  facts,  strictly  speak- 


THE    CEREBELLUM    AND    MOTILITY  177 

ing,  do  not  enter  into  the  type  of  catalepsy  described  by  M. 
Babinski  and  approach  more  the  abnormal  attitudes,  or  the  per- 
sistence of  given  attitudes  which  have  been  noted  by  various 
authors  in  animals  deprived  of  the  cerebellum  (Lewandowsky 
and  Munk). 

Finally,  I  admit  that  the  functions  of  the  cerebellum  are  not 
limited  to  the  equilibration  of  the  body,  and  that  the  inhibitory 
and  tonic  action  of  the  cerebellum  makes  itself  felt  in  all  move- 
ments and  all  attitudes.  But  as  regards  the  disturbances  of  equi- 
librium in  cerebellar  patients  and  in  animals  deprived  of  the  cere- 
bellum, they  appear  to  me  to  depend  not  only  upon  the  loss  of 
the  tonic  and  regulatory  action  of  each  muscle  which  enters  into 
contraction,  but  also  to  a  lack  of  tonic  synergy  in  the  muscular 
groups  which  act  together  in  the  maintenance  of  equilibrium  for 
a  given  movement. 

I  recall,  therefore,  the  conclusions  which  I  formulated  in  my 
thesis  in  1897.  "  The  cerebellum  should  be  considered  as  an 
organ  developing  itself  in  the  course  of  the  sensory  paths,  with 
which  it  enters  into  relations  in  the  adult,  by  more  than  one  bundle 
of  fibers.  It  registers  peripheral  and  central  excitations  and  im- 
pressions and  reacts  upon  one  and  the  other.  It  is  not  the  seat 
of  any  peculiar  sense  but  the  seat  of  a  particular  reaction  put 
into  play  by  various  excitations.  This  reaction  applies  itself  to 
the  maintenance  of  equilibrium  in  the  various  forms  of  attitudes 
or  actions  reflex,  automatic  or  voluntary.  It  is  a  reflex  center 
of  equilibration."  I  had,  then,  in  view  particularly  the  equilibra- 
tion of  the  body  in  general ;  during  walking  and  during  the 
upright  position.  But  on  account  of  the  tremor  of  the  limbs  and 
of  the  too  sudden  movements  noted  in  a  number  of  observations 
I  likewise  supposed  that  the  cerebellum  intervened  in  the  main- 
tenance of  equilibrium  of  the  different  parts  of  the  body  and  of 
the  limbs  in  particular.  Is  it  not  logical,  indeed,  to  consider  as 
a  perturbation  of  equilibrium  the  difficulty  or  impossibility  in 
which  animals  or  individuals  deprived  of  their  cerebellum  find 
themselves  to  obtain  perfect  and  immediate  stability  in  the  execu- 
tion of  various  movements,  or  in  the  taking  of  an  attitude? 

It  is  in  the  vermis  and  perhaps  also  in  the  lateral  lobe  that 
the  tonic  function  of  the  cerebellum  which  is  adapted  to  the  main- 
tenance of  equilibrium  and  the  attitudes  and  displacements  of  the 
13 


1/  THE   FUNCTIONS   OF   THE   CEREBELLUM 

body  is  seated.  It  is  exercised  under  the  influence  of  peripheral 
excitations  which  come  to  the  vermis  traversing  the  restiform 
bodies  (fibers  of  medullary  and  spinal  origin),  or  central  excita- 
tions which  leave  the  cerebral  cortex  and  reach  the  lateral  lobe 
after  having  followed  the  crural  path,  the  superior  layer  of  the 
pons,  and  the  middle  cerebellar  peduncle.  Among  these  central 
excitations  those  which  come  from  the  cortex  of  the  temporal 
lobe,  passing  by  the  bundle  of  Turck,  deserve  special  mention,  since 
their  center  of  origin  is  considered  by  Mills  as  being  a  center  of 
labyrinthine  representation.  This  is  why  we  cannot  exclude  the 
lateral  lobe  from  the  centers  which  preside  over  the  functions  of 
equilibration.  According  as  to  whether  it  is  the  vermis  or  the 
lateral  lobe  which  enters  into  activity,  the  centrifugal  excitations 
follow  the  nucleus  of  the  roof,  and  the  cerebello-vestibular  bun- 
dles in  the  first  case,  and  the  dentate  nucleus  and  the  superior 
cerebellar  peduncle,  in  the  second.  In  the  first  case,  they  end  in 
the  motor  spinal  centers  through  the  intermediation  of  the  ves- 
tibular  nuclei,  or  the  descending  cerebellar  bundles.  In  the  sec- 
ond case,  they  do  not  end  there  until  they  have  traversed  either 
the  red  nucleus  (cerebello-  rubro-spinal  path)  or  the  thalamusand 
the  cerebral  cortex  (cerebello-thalamo-cortico-spinal  path).  It 
is  probable  that  the  regulatory  function  of  movements  has  its 
principal  seat  in  the  lateral  lobe  and  that  it  is  exercised  under  the 
control  and  command  of  the  cerebral  cortex  by  the  intermediation 
of  the  cerebro-rubro-spinal  path,  and  the  cerebro-thalamo-cortico- 
spinal  path  (see  Figs.  28  and  29,  pages  39  and  41). 

These  considerations  have  for  a  basis  the  notions  of  normal 
and  comparative  anatomy,  and  also  clinical  and  experimental 
facts.  Sections  of  the  superior  cerebellar  peduncle  are  followed 
by  a  homolateral  tremor  of  the  limbs  analogous  to  that  of  mul- 
tiple sclerosis,  likewise  in  man,  lesions  of  the  tegmentum,  which 
destroy  the  red  nucleus,  or  the  superior  cerebellar  peduncle,  give 
rise  to  the  same  phenomena  (syndrome  of  Benedict). 

But  in  their  intimate  mechanism,  these  coordinations  are  not 
identical  in  man  and  in  the  various  types  of  the  animal  series, 
because  the  anatomical  centers  which  enter  into  play  have  neither 
the  same  importance  nor  the  same  structure.  The  red  nucleus 
in  man  and  in  the  anthropoids,  to  give  only  one  example,  is  not 
the  same  as  it  is  in  the  inferior  mammals  (Monakow).  The 
rubro-spinal  bundle  is  rudimentary  in  the  higher  apes  and  in  man. 


THE  CEREBELLUM  AND  MOTILITY  179 

SUBSTITUTION  FOR  THE  CEREBELLUM  BY  THE  CEREBRUM 

The  observation  of  animals  which  have  been  deprived  of  their 
cerebellum  shows  that  this  organ  is  partially  supplied  by  other 
centers.  At  first,  particularly  as  concerns  equilibrium,  it  seems 
that  the  two  halves,  or  even  the  various  parts  of  the  cerebellum, 
can  substitute  for  one  another  to  a  certain  degree.  The  charac- 
ters of  movement,  which  become  more  intentional,  lets  one  sup- 
pose that  a  large  part  is  attributable  to  the  cerebrum,  and  more 
particularly  to  the  motor  zone  of  the  cerebral  cortex.  This  influ- 
ence seems  to  be  again  demonstrated  by  the  fact  that  in  a  dog 
deprived  of  half  of  the  cerebellum,  and  already  very  much  im- 
proved, the  disturbances  of  equilibrium  reappear  when  its  atten- 
tion is  distracted. 

In  man  the  progressive  atrophies  do  not  ever  give  rise  to  dis- 
orders so  intense  as  in  an  animal  immediately  after  an  operation. 
The  restoration  of  the  function  is  contemporaneous  with  its  pro- 
gressive weakening  and  partially  masks  it.  This  restoration  is 
also  due  to  the  substitution  for  the  cerebellum  by  the  cerebrum. 

Luciani  has  shown  that  a  dog  deprived  of  its  cerebellum  from 
which  the  two  sigmoid  gyri  had  also  been  removed,  became  inca- 
pable of  learning  to  walk  or  to  stand  upright  again,  even  several 
months  after  the  second  operation.  Similar  observations  have 
been  made  by  O.  Polimanti,  who  observed  that  the  disturbances 
consecutive  to  the  destruction  of  one  half  of  the  cerebellum  were 
augmented  after  the  ablation  of  the  frontal  lobe  of  the  opposite 
side.  This  author  believes  that  the  frontal  lobes  contribute  in  a 
measure  to  the  maintenance  of  equilibrium,  particularly  to  the 
maintenance  of  the  coarse  equilibrium  of  Munk. 

The  following  anatomo-clinical  observation  can  be  compared 
with  this  fact.  In  a  woman  aged  fifty- four  years  affected  with 
olivo-ponto-cerebellar  atrophy  (diagnosis  verified  by  autopsy), 
the  disturbances  of  equilibrium,  of  station,  and  of  gait,  nystagmus 
and  scanning  speech,  were  so  marked  that  the  diagnosis  of  mul- 
tiple sclerosis  had  been  made.  Dr.  Touche  gave  me  the  speci- 
mens for  a  histological  examination  by  serial  section  (Figs.  74 
to  76).  This  examination  demonstrated  that  besides  the  cere- 
bellar  atrophy  there  was  a  bilateral  lesion  of  the  cerebral  pedun- 
cles. In  the  sections  colored  by  the  method  of  Weigert-Pal  the 
bundle  of  Tiirck  and  the  internal  three  fifths  were  completely 


i8o 


THE   FUNCTIONS   OF   THE   CEREBELLUM 


decolored.  The  large  fibers  were  less  numerous  in  this  case  and 
the  fine  fibers  were  abundant.  The  neuroglia  was  proportion- 
ately proliferated.  Lower  down  in  the  superior  half  of  the  pons 
some  small  bundles  of  the  crural  path  were  also  manifestly  degen- 
erated. The  pyramids  were  absolutely  intact.  Histologically  the 
lesion  was  quite  comparable  to  that  of  multiple  sclerosis.  How- 
ever, in  no  part  were  patches  of  sclerosis  found.  Compared  to 
other  reported  observations  of  cerebellar  atrophy,  this  obser- 
vation is  very  important.  It  demonstrates  that  the  disturbances 


lole  ciiaarilatere 
postfrieur- 
*L Ssrnf 


100 


Crst 


FIG.  74.  Transverse  section  of  the  medulla  and  the  cerebellum  in  a 
case  of  olivo-ponto-cerebellar  atrophy,  associated  with  a  double  peduncular 
lesion  (Weigart-Pal  stain).  Atrophy  of  the  cortex  and  the  white  sub- 
stance of  the  cerebellum  (SbL).  Atrophy  of  the  medullary  olives  (Oi), 
and  the  restiform  body  (Crsf).  Relative  integrity  of  the  cerebellar  olive 
(OC).  (Andre-Thomas,  Revue  Neurologique,  1905.) 

due  to  atrophy  of  the  cerebellum  are  accentuated  by  the  fact  of 
the  interruption  of  the  cortico-motor  path,  and  consequently  that 
the  cerebral  cortex  substitutes  in  a  large  measure  the  cerebellum. 
What  happens  to  the  electrical  excitability  of  the  cerebral 
cortex  after  the  destruction  of  the  cerebellum  ? 


THE    CEREBELLUM    AND    MOTILITY 


181 


Russell  noted  that  ten  or  fifteen  minutes  after  unilateral  de- 
struction of  the  cerebellum  the  cerebral  hemisphere  of  the  oppo- 
site side  is  more  excitable  than  the  homolateral  hemisphere.  The 
difference  of  excitability  amounts  to  200  to  300  on  the  scale  of 
Kronecker.  The  same  results  have  been  registered  three  months 
after  the  operation.  If,  in  an  animal,  from  which  half  the  cere- 
bellum has  been  removed,  intravenous  injections  of  absinth  are 


FIG.  75.  Same  case  as  the  preceding  figure.  Transverse  section  of  the 
pons.  Atrophy  of  anterior  surface  and  total  degeneration  of  the  median 
cerebellar  peduncle  (Pcm).  Integrity  of  the  superior  cerebellar  peduncle 
(Pcs),  and  of  the  crural  path  (VP). 

made,  the  convulsions  are  much  more  intense  on  the  side  corre- 
sponding to  the  hemisphere  removed  (Figs.  77  and  78).  Luciani 
has  made  analogous  observations.  Electrical  excitations  of  the 
cerebral  cortex  on  the  side  opposite  the  destruction  of  the  cere- 
bellum produces  reactions  which  are  stronger  for  the  majority 
of  the  points  excited.  Bianchi,  on  the  contrary,  has  found  that 
the  motor  reactions  determined  by  excitation  of  the  cortex  are 
not  modified  by  partial  total  destruction  of  the  cerebellum.  If 
in  reality  the  excitability  is  augmented,  one  may  conclude  that 
each  cerebellar  hemisphere  exercises  a  crossed,  braking  action  on 
the  motor  cortical  zone.  This  exaggeration  of  excitability  ac- 


182 


THE   FUNCTIONS   OF   THE   CEREBELLUM 


cords  very  well  with  dysmetria  and  the  epileptoid  character  of 
movement  noted  in  man  and  in  animals,  in  the  case  of  the  enfee- 
blement  or  disappearance  of  the  cerebellar  function. 

The  cerebrum  supplants  the  cerebellum  not  only  as  a  motor 
center  but  also  as  a  sensory  center.  The  elaboration  of  periph- 
eral impressions  appears  to  play  a  certain  role. 


CL 


FIG.  76.  Same  case  as  the  preceding  figures.  Degeneration  of  the 
internal  three  fifths  of  the  crtis  cerebri  and  of  the  external  fifth,  or  bundle 
of  Turck  (FT).  Integrity  of  the  red  nucleus. 

When  a  dog  has  partially  reacquired  the  function  of  equi- 
librium after  the  total  destruction  of  the  cerebellum,  he  presents 
the  graver  cerebellar  and  ataxic  disturbances  in  the  posterior  ex- 
tremities if  the  posterior  lumbar  roots  are  sectioned  (Bickel  and 
Jacob). 


THE   CEREBELLUM    AND    MOTILITY  183 

The  influence  of  the  peripheral  excitations  which  -come  from 
the  labyrinth  is  still  more  remarkable.  In  a  dog  upon  which  I 
made  an  intracranial  section  of  both  eighth  nerves,  the  cerebellum 
was  totally  destroyed  about  a  month  after  the  first  operation. 


FIG.  77.  This  and  the  following  figure  are  borrowed  from  Risien 
Russell.  Experimental  researches  into  the  functions  of  the  cerebellum. 
Philosophical  Transactions  of  the  Royal  Society  of  London.  Vol.  185,  pp. 
819-861.  Convulsions  produced  by  absinthe  in  a  normal  dog.  Record  of 
the  extensor  muscles  of  the  anterior  extremities. 

He  was  unable  to  learn  to  walk  again,  or  even  to  stand  upright. 
The  two  front  legs  were  folded  under  the  body;  he  made  some 
efforts  to  raise  himself  and  walk,  but  he  fell  immediately  on  his 


1 84 


THE    FUNCTIONS    OF    THE    CEREBELLUM 


side  and  nearly  always  on  the  right  side.1  During  the  taking  of 
food  the  head  oscillated  violently  and,  although  he  was  well  fed, 
emaciation  was  very  marked.  Sixty  days  after  the  operation  the 


FIG.  78.     Convulsions  produced  by  absinthe  in  a  dog  deprived  of  the 

left  lateral  lobe  of  the  cerebellum.    Record  of  the  extensor  muscles  of  the 

anterior  extremities.     To  the  left  (L)  the  shocks  are  greater  than  to  the 
right  (/?). 

animal  had  made  no  progress,  either  towards  walking  or  stand- 
ing upright. 

1  The  examination  of  the  neuraxis  in  a  series  of  sections  revealed 
besides  the  destruction  of  the  cerebellum,  and  the  bilateral  section  of  the 
eighth  pair,  a  lesion  of  the  nuclei  of  the  posterior  column  on  the  right; 
the  triangular  auditory  nucleus  and  the  nucleus  of  Bechterew,  on  the 
same  side,  were  also  slightly  affected. 


THE    CEREBELLUM    AND   MOTILITY  185 

The  simultaneous  destruction  of  a  cerebellar  hemisphere  and 
the  eighth  nerve  of  the  same  side  provokes  disorders  of  an  inten- 
sity and  a  duration  far  greater  than  the  simple  section  of  a  cere- 
bellar hemisphere  (Figs.  43  to  45).  The  movements  of  rotation 
persist  much  longer  and  it  is  the  same  for  the  other  cerebellar 
symptoms.  In  an  animal  deprived  of  the  cerebellar  hemisphere 
and  of  the  vestibular  nerve  of  the  right  side  in  a  first  operation 
the  left  sigmoid  gyrus  was  removed  over  seventy  days  later. 
The  movements  of  rotation  reappeared  with  extreme  intensity 
and  persisted  for  about  twenty  days.  They  were  made  in  the 
same  direction  as  after  the  first  operation.  (This  is  a  new  argu- 
ment against  the  irritative  nature  of  the  movements  of  rotation.) 
The  disorders  of  motility  reappeared  with  greater  intensity  and 
three  months  after  the  second  operation  the  animal  was  incapable 


FIG.  79.  The  same  dog  as  the  one  represented  in  Figs.  43,  44  and 
45,  after  destruction  of  the  left  sigmoid  gyrus.  Repeated  falls  on  the 
right  side. 

of  standing  up  or  of  walking.  At  each  attempt  it  fell  almost 
immediately  to  the  right,  i.  e.,  to  the  side  of  the  cerebellar  lesion 
(Fig.  79). 

Another  dog  which  was  operated  upon  on  three  occasions  for 
section  of  the  right  auditory  nerve,  ablation  of  the  sigmoid  gyrus 
on  the  left  side,  and  destruction  of  the  right  cerebellar  hemisphere, 
was  unable  to  reeducate  itself  after  the  last  operation.  After  the 
second  operation  there  was  a  recrudescence  of  the  symptoms. 

Experiments  of  the  same  type  have  been  made  upon  pigeons 
by  Lange.  This  author  destroyed :  First,  the  labyrinth  in  animals 
which  had  previously  suffered  a  destruction  of  the  cerebellum : 
Second,  the  cerebellum  in  animals  which  had  previously  suffered 
the  destruction  of  the  labyrinth. 


1 86  THE   FUNCTIONS   OF   THE   CEREBELLUM 

In  the  first  case  the  movements  of  rotation  of  the  head  ap- 
peared sooner.  These  movements  were  very  disordered:  there 
were  tumbles  backward  and  to  the  right,  inability  to  stand  upon 
the  legs,  emaciation  was  rapid  and  the  animals  showed  no  ten- 
dency towards  an  amelioration  of  their  condition.  In  the  second 
case  if  the  operation  is  performed  at  a  time  when  the  animal  only 
presents  those  symptoms  discoverable  by  delicate  means  of  exami- 
nation, the  disturbances  which  follow  the  extirpation  of  the  cere- 
bellum are  the  same  as  those  which  follow  a  simple  cerebellar 
extirpation,  but  the  tendency  to  draw  back  is  more  marked  and 
the  symptoms  show  a  greater  intensity. 

The  substitution  of  the  cerebellum  by  the  other  nerve  centers, 
and  more  particularly  by  the  cerebrum,  raises  a  delicate  question 
of  pathological  physiology.  Without  counting  the  cases  of  soften- 
ing limited  to  the  cerebellar  cortex  which  have  shown  no  clinical 
expression,  how  can  we  explain  the  complete  agenesis  of  a  cere- 
bellar hemisphere  which  has  shown  itself  only  as  post-mortem 
finding  and  has  not  affected  the  functional  locomotion  or  motility. 
Several  hypotheses  can  be  proposed  to  explain  a  fact  apparently 
so  paradoxical;  either  there  may  be  a  substitution  for  the  absent 
cerebellar  hemisphere  by  the  cerebellar  hemisphere  which  is  pres- 
ent, or  it  may  be  substituted  by  the  cerebral  hemisphere  of  the 
opposite  side  or  perhaps  both  these  methods  of  substitution  are 
associated.  In  the  observations  of  total  agenesis  of  the  cerebel- 
lum it  is  rare  that  disturbances  of  motility  and  locomotion  are  not 
mentioned.  More  often  it  is  true  these  disturbances  have  not 
been  analyzed  and  it  is  difficult  in  merely  reading  of  them  to  con- 
ceive an  exact  idea  of  their  nature.  It  is  nevertheless  surprising, 
to  only  cite  one  example,  that  the  extreme  smallness  of  the  cere- 
bellum in  the  patient  of  Oddo  had  not  occasioned  any  motor  dis- 
orders. It  is  clearly  specified  in  this  observation  that  the  move- 
ments were  forceful  and  dextrous,  but  febrile  and  impulsive. 
This  time  also  we  must  have  recourse  to  the  preceding  hypotheses 
in  order  to  explain  the  absence  of  symptoms  and  must  invoke  the 
idea  of  cerebral  substitution.  Perhaps,  if  in  those  individuals  in 
whom  the  cerebellum  is  either  only  partially  developed  or  totally 
lacking,  the  symptomatology  is  more  abortive  than  in  those  indi- 
viduals who  at  a  more  advanced  age  are  affected  by  a  cerebellar 
lesion,  it  is  because  in  the  last  case  one  must  take  into  account 


THE    CEREBELLUM    AND   MOTILITY  187 

not  only  the  functional  suppression  of  the  cerebellum  but  also 
the  secondary  modifications  introduced  into  the  functioning  of 
other  organs  by  the  derangement  of  a  mechanism  with  which  they 
have  always  been  associated.  A  priori  it  seems  logical  to  admit 
that  the  substitution  is  more  easily  made,  and  more  complete  the 
earlier  it  takes  place,  and  before  it  has  been  affected  by  previous 
habits.  Finally,  the  variations  of  one  case  from  another  may  be 
explained  by  individual  differences  which  are  the  more  accentuated 
as  the  subject  is  higher  in  the  animal  scale.  The  same  is  the  case 
in  all  other  cerebral  involvements. 

ANALOGIES  BETWEEN  THE  PHENOMENA  FOLLOWING  SECTION  OF 
THE  EIGHTH  PAIR  OF  NERVES  AND  THOSE  FOLLOWING  THE 
DESTRUCTION  OF  THE  CEREBELLUM.     ANATOMICAL  AND 
PHYSIOLOGICAL  RELATIONS  BETWEEN  THE  LABY- 
RINTH AND  THE  CEREBELLUM 

There  exist  between  these  two  orders  of  phenomena  some 
very  marked  analogies.  For  Flourens  the  cerebellum  is  a  center 
of  coordination  and  equilibrium  and  the  nerves  of  the  semicircular 
canals  collaborate  equally  in  the  maintenance  of  equilibrium  by 
means  of  their  moderating  action.  Goltz  also  makes  of  the  semi- 
circular canals  an  organ  of  equilibrium.  Later  Ewald  brought  to 
light  the  influence  of  the  labyrinth  upon  the  precision  of  move- 
ments, and  he  invented  a  theory  which  I  will  have  occasion  to 
refer  to  later.  I  will  content  myself  by  citing  the  opinions  of  a 
number  of  the  more  celebrated  physiologists  who  have  made  a 
study  of  the  functions  of  the  labyrinth,  of  the  eighth  pair  of 
nerves,  and  of  the  semicircular  canals.  It  is  admitted  that  the 
motor  disturbances  which  follow  section  or  lesion  of  the  eighth 
pair  of  nerves  are  caused  by  the  perturbation  or  the  abolition  of 
the  functions  of  the  semicircular  canals,  of  the  utricle  and  of  the 
saccule ;  that  is  to  say,  of  those  parts  which  are  innervated  by  the 
vestibular  nerve. 

The  symptoms  following  section  of  the  eighth  pair  should  be 
studied  in  cases  of  unilateral  section  and  in  cases  of  bilateral  sec- 
tion. With  the  object  of  facilitating  comparison  with  the  dis- 
turbances consecutive  to  the  destruction  of  half,  or  of  the  whole 
of  the  cerebellum,  I  will  recall  the  result  of  my  personal  experi- 


I  88  THE   FUNCTIONS   OF   THE   CEREBELLUM 

ments  upon  the  dog,2  since  it  is  also  upon  this  animal  that  I  have 
studied  with  greater  detail  the  phenomena  produced  by  destruc- 
tion of  the  cerebellum. 

Unilateral  Section  of  the  Labyrinthine  Root  is  sometimes  fol- 
lowed by  a  movement  of  rotation  around  the  longitudinal  axis,  but 
this  movement  is  isolated  and  not  reproduced  in  series  as  after 
the  destruction  of  half  of  the  cerebellum. 

In  certain  animals,  such  as  the  rabbit,  unilateral  section  of  the 
auditory  nerve  is  followed  by  movements  of  rotation  around  the 
longitudinal  axis.  In  the  dog  movements  in  a  circle  or  like  the 
spokes  of  a  wheel  are  usually  observed  (Figs.  80  and  81). 


FIG.  80.     Movements  of  rotation  in  a  circle.    Section  of  the  right 
labyrinthine  root  in  the  dog. 

The  combination  of  section  of  the  left  labyrinthine  root  and 
the  right  cerebellar  hemisphere  gives  rise  to  a  peculiar  movement 
of  rotation  represented  in  Fig.  82.  The  head  is  inclined  towards 
the  side  of  the  section  and  at  the  same  time  there  is  a  torsion,  so 
that  half  of  the  face  (on  the  side  of  the  lesion)  is  on  an  inferior 
plane.  After  the  hemi-destruction  of  the  cerebellum  the  inclina- 
tion is  more  marked  and  the  torsion  less  so. 

The  deviation  of  the  eyes  is  such  that  the  eye  of  the  injured 
side  looks  downwards  and  slightly  inwards,  the  eye  of  the  unin- 

2  These  results  coincide  with  those  of  other  authors. 


THE    CEREBELLUM    AND   MOTILITY 


189 


jured  side  looks  slightly  upwards  and  outwards  (Fig.  83).     Dur- 
ing the  first  few  days  some  nystagmic  oscillations  are  seen,  which 


FIG.  81.     Movement  of  rotation  like  the  spokes  of  a  wheel.     Section  of 
right  labyrinthine  root  in  the  dog. 


FIG.  82.  Movement  of  rotation  analogous  to  that  of  the  needle  of  a 
compass.  Section  of  the  left  labyrinthine  root  and  the  right  cerebellar 
hemisphere. 

have  for  their  object  the  replacing  of  the  eyeballs  in  their  normal 
position. 

The  limbs  of  the  side  operated  upon  are  weaker  and  the  animal 


190 


THE   FUNCTIONS   OF   THE   CEREBELLUM 


often  sinks  down  with  his  paws  bent  under  him.  Those  of  the 
healthy  side  are  in  abduction.  This  is  augmented  when  the  ani- 
mal tries  to  jump  towards  a  person  and  a  fall  takes  place  upon  the 
injured  side. 

If  the  fore  paws  are  seized  in  the  hand  so  as  to  make  the  dog 
walk  on  his  hind  paws,  the  paw  of  the  injured  side  is  lifted  less 
easily  from  the  ground  and  carried  forward  more  suddenly. 

The  power  to  swim  is  preserved,  although  in  the  beginning 


FIG.  83.     Inclination  and  rotation  of  the  head  and  of  the  eyes  in  a  dog 
whose  eighth  nerve  had  been  sectioned  on  the  right  side. 

the  movements  are  irregular  and  disordered,  but  they  become 
normal  very  rapidly.  The  resistance  to  movements  of  propul- 
sion, retropulsion  and  lateropulsion  (particularly  towards  the 
operated  side)  is  very  much  diminished.  Placed  on  a  movable 
surface  he  does  not  resist  the  inclination  of  the  surface  so  well  as 
a  normal  dog,  particularly  when  the  surface  is  inclined  laterally 
and  towards  the  side  of  the  lesion. 

Submitted  to  centrifuging  the  reactions  of  the  head  differ 
from  those  of  a  normal  dog,  particularly  when  the  animal  is  turned 
towards  the  side  of  the  lesion. 

The  movements  in  a  circle,  the  ocular  deviations,  the  attitudes 


THE    CEREBELLUM    AND    MOTILITY  1 9! 

of  the  head,  and  the  awkwardness,  attenuate  progressively.  The 
inclination  of  the  head  and  the  torsion  are  the  most  persistent 
symptoms. 

After  Bilateral  Section  of  the  Eighth  Pair  of  Nerves  the  head 
oscillates  in  every  direction :  jt  is  very  mobile  and  does  not  resist 
movements  which  are  imparted  to  it.  During  walking  the  limbs 
are  in  slight  abduction,  the  head  describes  oscillations  of  great 
amplitude ;  this  is  why  the  animal  advances  in  a  wavy  line,  he 
walks  in  zigzags.  The  instability  of  the  head  appears  to  be  the 
cause  of  these  irregularities  of  gait,  whereas  in  the 'cerebellar  gait 
the  whole  body  is  displaced,  at  the  same  time,  as  an  entity.  In 
running  the  progress  is  interrupted  by  falls  either  to  the  right  or 
to  the  left,  or  by  movements  in  a  circle. 

Walking  on  the  hind  paws  is  difficult.  The  paws  are  raised 
from  the  ground  with  great  pains  and  then  thrust  suddenly  for- 
ward. If  the  animal  is  held  so  that  it  stands  upon  its  hind  paws 
in  an  almost  vertical  position  and  then  released,  it  falls  almost 
immediately  backwards.  During  the  first  days  it  has  more  diffi- 
culty in  seizing  its  food  and  swallows  it  slowly.  During  prehen- 
sion of  the  food  the  oscillations  of  the  head  are  augmented  in 
frequency  and  amplitude ;  the  same  phenomenon  takes  place  when 
it  drinks.  This  muscular  atony  is  not  limited  to  the  muscles  of 
the  head  or  of  the  neck.  It  may  be  observed  in  the  muscles  of 
the  jaw.  The  mouth  may  be  widely  opened  and  kept  open  with- 
out its  manifesting  the  slightest  resistance. 

It  is  unable  to  jump;  placed  upon  a  table  it  approaches  its 
head  near  to  the  edge  but  instead  of  gathering  itself  together  for 
a  jump  like  a  normal  dog,  it  allows  itself  to  fall  in  a  lump.  The 
hind  quarters  pass  over  the  head  and  it  turns  a  somersault. 

The  first  days  which  follow  the  operation  it  does  not  seem  to 
have  an  exact  notion  of  its  situation  in  space.  Upon  a  young 
dog  which  had  been  submitted  to  a  bilateral  section  of  the  audi- 
tory nerve  I  performed  the  following  experiment:  Suspended 
gently  by  the  hind  legs  the  animal  sought  to  defend  itself  by  rais- 
ing the  head,  placing  the  front  legs  in  extension  and  bending  the 
trunk.  When  this  experiment  was  repeated,  after  having  sup- 
pressed the  control  of  vision  by  blindfolding  it,  the  animal  did 
not  attempt  any  movements  whatever.  It  remained  suspended 
in  an  inert  mass.  The  same  experiment  repeated  the  first  days 
after  the  operation  always  gave  the  same  results  (Figs,  i  and  2). 


THE   FUNCTIONS   OF   THE    CEREBELLUM 

At  the  end  of  several  days  the  animal  protects  itself  just  as 
well  with  the  eyes  closed  as  with  them  open. 

The  descent  of  a  stairway  is  impossible  or  very  difficult.  The 
animal  is  very  well  aware  of  this,  and  when  it  is  pushed  towards 
a  stairway  it  tries  to  escape  to  one  side.  If  it  is  obliged  to  de- 
scend it  loses  its  equilibrium  and  rolls  down  like  a  ball.  The 
ascension  of  a  stairway  is  less  difficult ;  nevertheless,  it  frequently 
falls  backward. 

If  the  animal  is  held  above  the  ground  and  allowed  to  fall  sud- 
denly it  falls  in  a  heap. 

All  these  disturbances  attenuate  progressively  and  more  rap- 
idly if  the  animal  is  constantly  at  liberty.  But  certain  symptoms 
persist  much  longer.  These  are  the  awkwardness  during  jump- 
ing, the  difficulty  of  descending  a  stairway,  and  principally  the 
impossibility  of  swimming,  a  fact  to  which  attention  has  not  per- 
haps been  sufficiently  attracted.  When  the  animal  is  plunged  in 
the  water  it  commences  immediately  to  turn  around  its  longi- 
tudinal axis,  either  from  right  to  left  or  from  left  to  right,  and 
then  sinks  in  the  water  and  would  drown  if  it  were  not  saved. 
Finally,  we  repeated  the  experiments  of  Goltz  and  Ewald.  These 
authors  remarked  that  a  pigeon  deprived  of  its  semicircular  canals 
was  no  longer  capable  of  reacting  by  appropriate  muscular  adapta- 
tions. I  undertook  experiments  of  the  same  kind  upon  three 
dogs,  which  had  previously  been  submitted  to  a  bilateral  section 
of  the  eighth  pair.  With  this  object  the  animal  was  placed  upon 
a  plank,  movable  around  a  horizontal  axis,  either  parallel  or  at 
right  angles  to  this  axis.  The  eyes  were  blindfolded.  The  reac- 
tions were  then  studied  in  the  movements  of  inclination  of  the 
board,  both  slow  and  sudden.  If  this  experiment  were  made  with 
a  normal  dog  and  under  the  same  conditions,  it  reacted  by  appro- 
priate movements  which  were  very  easy  to  observe  during  the 
slow  inclinations.  These  movements  prevented  it  from  falling 
forward  or  on  the  sides,  according  to  its  situation  in  relation  to 
the  axis.  In  the  more  sudden  inclinations  it  reacted  also  in  a 
manner  to  avoid  a  fall,  or  it  jumped.  If  now  the  experiment  is 
repeated  upon  the  dog  upon  which  the  double  section  of  the  eighth 
pair  has  been  performed,  some  days  after  the  section,  the  normal 
reactions  are  no  longer  produced  and  a  very  slight  inclination  of 
the  board  is  enough  to  cause  the  animal  to  fall  and  roll  on  the 


THE   CEREBELLUM    AND   MOTILITY  193 

side  if  it  is  placed  parallel  to  the  axis  of  rotation,  or  it  falls  back- 
wards or  forwards  if  it  is  placed  at  right  angles  to  this  axis,  the 
head  being  to  the  side  of  the  inclination  in  the  first  case  and  the 
tail  in  the  second.  These  reactions  take  place  in  a  more  marked 
degree  as  the  inclination  is  more  sudden. 

This  experiment  has  been  repeated  several  times  upon  the 
same  animal  several  weeks  and  even  more  than  two  months  after 
the  section  of  the  auditory  nerve;  with  the  slow  inclination  it 
reacted  then  a  little  better ;  but  a  very  great  inclination  is  not  nec- 
essary for  the  animal  to  tumble  or  roll  over,  as  it  is  the  first  days 
after  the  section.  The  amelioration  which  is  produced  during 
the  slow  inclination  seems  to  be  due  to  a  substitution  by  peripheral 
impressions,  the  sensations  furnished  by  the  sliding  of  the  paws 
warning  the  animal  of  the  modification  which  has  taken  place  in 
its  situation. 

Falls  upon  the  side  or  backwards  or  forwards  are  also  pro- 
duced when  the  animal  is  placed  upon  a  board  to  which  move- 
ments of  lateropulsion,  propulsion  or  retropulsion  are  given. 

Some  weeks  after  the  operation  it  walks  almost  as  well  as  a 
normal  dog  and  keeps  its  equilibrium  very  well,  either  when  stand- 
ing or  when  walking. 

The  disturbances  of  equilibrium  and  of  motility  have  been 
mentioned  by  several  authors  in  patients  affected  by  disease  of 
the  inner  ear.  Incoordination  and  the  disturbances  of  equilibrium 
are  a  part  of  the  syndrome  described  under  the  name  of  the  vertigo 
of  Meniere.  Van  Stein  has  insisted  upon  the  disturbances  of 
static  and  dynamic  equilibrium  in  diseases  of  the  ear,  and  his 
observations  have  been  many  times  confirmed.  Voltolini  has  also 
called  attention  to  these  facts. 

In  labyrinthine  otitis,  as  well  as  in  cerebellar  disease,  the 
upright  position  cannot  be  maintained  except  with  the  feet  spread 
apart — the  base  of  support  is  enlarged.  The  patient  cannot 
stand  upon  one  leg.  The  gait  is  uncertain,  the  body  being  car- 
ried alternately  from  one  side  to  the  other.  The  steps  are  un- 
equal and  irregularly  spaced.  Muscular  energy  is  very  much  di- 
minished and  fatigue  ensues  rapidly.  The  labyrinthine  ataxia 
differs  however  from  the  cerebellar  ataxia.  The  sign  of  Rom- 
berg  is  the  rule.  The  variations  of  the  attitude  of  the  head 
augment  considerably  the  disturbances  of  equilibrium.  The  mus- 


194  THE    FUNCTIONS   OF   THE    CEREBELLUM 

cular  weakness  is  more  pronounced,  and,  moreover,  when  the 
patient  is  subjected  to  passive  movements  of  rotation  or  transla- 
tion, the  orientation  of  these  movements  is  no  longer  perceived; 
the  nystagmus  and  rotatory  vertigo,  which  appear  in  a  normal 
individual  after  rotation  around  the  longitudinal  axis,  have  dis- 
appeared. The  passage  of  a  galvanic  current  through  the  skull, 
in  the  line  of  the  two  ears,  no  longer  provokes  nystagmus  or  ver- 
vertigo. 

Disturbances  of  equilibrium  have  been  noted  in  deaf  mutes, 
although  it  is  true  they  are  less  pronounced,  only  in  the  rough. 
James  observed  that  in  some  of  them  orientation  in  the  water  was 
impossible,  and  if  left  to  their  own  devices  they  would  drown. 
Animals  in  which  the  two  auditory  nerves  have  been  sectioned 
have  the  same  inability  to  direct  and  orient  themselves  in  water 
(Ewald,  Andre-Thomas).  Whereas,  for  animals  deprived  of 
the  cerebellum  swimming  is  still  possible  (Luciani,  Andre- 
Thomas). 

In  birds  the  horizontal,  sagittal  and  vertical  canals  may  be 
suppressed  at  will,  and  thereby  abnormal  attitudes  of  the  head 
produced,  varying  according  to  the  canal  injured,  also  troubles 
of  motility,  and  movements  in  a  circle.  When  all  the  canals  are 
•cut,  the  head  oscillates  in  every  direction,  like  a  pendulum,  and 
the  animal  is  no  longer  able  to  stand  upright  (Flourens). 

Finally,  between  the  disturbances  produced  by  section  of  the 
eighth  pair  of  nerves,  and  those  produced  by  destruction  of  the 
cerebellum,  there  exist  analogies  and  differences.  It  seems  that 
the  first  condition  gives  rise  to  defective  attitudes  of  the  head, 
and  that  the  disturbances  of  equilibrium  are  due  to  disorientation 
of  the  head.  The  musculature  of  the  head  is,  however,  not  alone 
in  question.  The  musculature  of  the  limbs  and  the  trunk  is  also 
disturbed. 

The  vestibular  apparatus,  and  by  this  general  term  we  must 
understand  the  semicircular  canals,  the  utricle  and  the  saccule, 
advises  us  as  to  the  attitude  and  progression  of  our  body  (otoliths 
of  the  saccule  and  the  utricle),  and  as  to  the  rotation  of  the  head 
(movements  of  the  endolymph  in  the  semicircular  canals) 
(Breuer,  Ewald).  But  it  seems  to  have  other  functions;  Ewald 
was  struck  by  the  diminution  of  muscular  force  and  the  lack  of 
coordination  of  certain  movements  in  the  animals  upon  which  he 


THE   CEREBELLUM    AND    MOTILITY  195 

operated;  the  muscles  contracted  either  too  slowly  or  too  late. 
He  admits  the  tonic  influence  of  the  labyrinth  upon  the  muscula- 
ture, the  existence  of  a  labyrinthine  tonus.  After  suppression  of 
the  labyrinth,  there  would  be  a  considerable  diminution  of  mus- 
cular energy,  and  the  muscles  most  effected  are  those  which  have 
need  of  precision  in  the  accomplishment  of  their  functions. 
Thus,  in  pigeons,  after  the  destruction  of  the  labyrinth,  there  was 
no  disturbance  in  the  functioning  of  the  muscles  of  the  legs  dur- 
ing walking,  whereas,  in  cockatoos,  who  use  the  muscles  of  the 
legs  and  the  feet  to  seize  their  food  and  to  climb,  there  was  a  very 
marked  disturbance. 

The  labyrinth,  according  to  Ewald,  reacts  upon  all  of  the 
muscles,  but  each  labyrinth  is  particularly  in  relation  with  the 
muscles  of  the  opposite  side,  which  move  the  vertebral  column 
and  the  head  (muscles  of  the  back  of  the  neck,  of  the  neck,  and 
muscles  which  go  from  the  body  of  one  vertebra  to  the  transverse 
processes  of  the  vertebra  above).  As  to  the  muscles  of  the  ex- 
tremities, each  labyrinth  is  in  relation  with  the  extensors  and 
abductors  of  the  same  side.  All  the  muscles  of  the  eyes,  with 
the  exception  of  the  external  rectus  (  ?)  seem  to  depend  prin- 
cipally upon  the  homonymous  labyrinth. 

In  conclusion,  the  continual  excitations  which  come  from  the 
labyrinth  are  transmitted  to  certain  nervous  centers,  which  reflect 
them  in  their  turn  to  the  muscles,  in  which  they  augment  the 
tonicity,  a  tonicity  which  is  accompanied  by  modifications  in  the 
terminal  organs  of  the  sensory  nerves  of  the  muscles.  This  laby- 
rinthine tonus,  when  it  begins  to  disappear,  results  at  the  same 
time  in  modifications  of  tonus  and  muscular  sensibility.  This  is 
why  the  movements  become  less  energetic,  and  less  precise. 

What  are  the  nerve  centers  that  govern  the  labyrinthine  tonus  ? 
The  resemblances  noted  above  between  the  cerebellar  symptoms 
and  the  labyrinthine  symptoms  allow  us  to  suppose  that  the  cere- 
bellum is  the  principal  of  these  centers.  Goltz  has  already  ad- 
vanced the  hypothesis  that  the  cerebellum  is  the  center  of  percep- 
tion of  attitudes  of  the  head.  The  proximity  of  the  cerebellum, 
and  the  nuclei  of  the  vestibular  nerve,  support  this  opinion. 
Luciani  has  returned  recently  to  this  subject,  and  he  assimilates 
almost  completely  the  phenomena  which  are  manifested  after 
the  destruction  of  the  labyrinth,  and  those  which  follow  the  de- 


196  THE   FUNCTIONS   OF   THE   CEREBELLUM 

struction  of  the  cerebellum.  The  destruction  of  either  one  or 
the  other  has  for  consequence  a  diminution  of  tonus ;  this  is  one 
of  the  points  upon  which  the  Florentine  physiologist  has  most 
insisted,  and  he  compares  the  cerebellar  tonus  with  the  laby- 
rinthine tonus.  He  pushes  too  far  the  resemblance  between  the 
cerebellar  symptoms  and  the  labyrinthine  disturbances.  The  mus- 
cular weakness  in  fact  is  much  more  marked  after  the  destruc- 
tion of  the  labyrinths.  "  At  Naples,  Ewald  saw  some  sharks 
which  required  four  vigorous  arms  to  hold  them,  and  were  held 
by  a  single  hand  after  the  section  of  the  auditory  nerves;  never- 
theless, after  the  removal  of  large  portions  of  the  cerebellum, 
which  constituted  a  much  graver  operation,  this  muscular  en- 
feeblement  did  not  take  place"  (Kcenig). 

The  cerebellum  is  not  a  center  of  perception  for  labyrinthine 
excitations.  Submitted  to  centrifugation,  individuals  affected 
with  atrophy  of  the  cerebellum  perceive  the  movements  of  rota- 
tion very  well,  the  reverse  of  those  affected  with  labyrinthine 
otitis.  The  fibers  of  the  vestibular  root  lose  themselves  almost 
entirely  in  the  medulla,  in  the  nuclei  of  Deiters,  Bechterew,  and 
in  the  triangular  auditory  nucleus.  The  fibers  which  go  to  the 
nucleus  of  the  roof  are  very  scanty.  Luciani  therefore  commits 
an  error  in  affirming  that  the  labyrinth  acts  upon  the  centers 
through  the  intermediation  of  the  cerebellum.  There  are,  never- 
theless, important  connections  between  the  labyrinthine  appara- 
tus and  the  cerebellum,  but  they  are  of  another  order.  The 
central  gray  nuclei  of  the  cerebellum,  the  nucleus  of  the  roof, 
the  globulus,  and  the  embolus,  and  perhaps  also  the  dentate 
nucleus,  give  rise  to  fibers  which  terminate  in  the  three  vestibular 
nuclei  (nucleus  of  Deiters,  nucleus  of  Bechterew,  and  the  trian- 
gular auditory  nucleus,  see  anatomy).  The  greater  number  of 
these  fibers  are  apparently  direct,  though  some  are  crossed  (Fig. 
84).  The  result  is  an  anatomical  disposition  altogether  unique, 
and  the  activity  of  the  vestibular  nuclei  may  be  brought  into  play, 
either  by  labyrinthine  excitations,  or  by  cerebellar  excitations. 
One  can  easily  conceive,  therefore,  that  the  suppression  of  one  or 
the  other  of  these  sources  of  excitation  should  have  in  both  cases 
very  comparable  results,  but  not  identical  ones,  for  the  excitations 
are  not  of  the  same  nature,  and  the  relations  of  each  category 
of  fibers  with  the  cells  of  these  three  nuclei  are  probably  not  the 


THE    CEREBELLUM    AND    MOTILITY 


I97 


same.  It  appears  to  be  demonstrated  that  the  vestibular  apparatus 
contributes  to  assure  the  maintenance  of  equilibrium  of  the  head 
and  of  the  trunk  in  passive  movements.  Does  the  cerebellum 
govern,  in  its  turn,  equilibration  in  active  movements  (voluntary, 


e  anl"? dc. <la 
•moslte, 


FIG.  84.  Diagram  representing  the  relations  of  the  central  nuclei  of 
the  cerebellum  with  the  nuclei  of  the  vestibular  nerve,  the  oculo-motor 
nuclei,  and  the  spinal  cord.  (This  diagram  redrawn  according  to  my 
direction  is  borrowed  from  the  work  of  E.  J.  Moure  and  Couzard  upon  the 
functional  examination  of  the  labyrinth,  1909.) 

automatic  and  reflex)  ?  This  seems  to  be  none  the  less  solidly 
established.  It  does  not  seem,  however,  that  it  exercises  this 
function  entirely  by  itself  to  the  exclusion  of  the  vestibular  appa- 
ratus. 


198  THE    FUNCTIONS   OF   THE   CEREBELLUM 

One  can  represent  in  a  different  manner  the  physiological  rela- 
tions between  the  cerebellum  and  the  labyrinth.  The  cerebellum 
has  a  moderating  action  in  regard  to  the  reflexes  provoked  by  the 
vestibular  apparatus  (in  moderating  the  reflex  tonus  through  the 
intermediation  of  the  nucleus  of  Deiters),  the  same  as  it  has  to- 
wards the  cerebral  impulsions  (Adler).  The  cerebellum  has, 
therefore,  an  action  antagonistic  to  the  cerebrum.  When  the 
vermis  is  destroyed,  or  the  bundles  which  unite  the  nuclei  of  the 
eighth  pair  are  interrupted,  the  vestibular  apparatus  works 
without  a  brake,  its  reactions  are  exaggerated  and  cerebellar  ataxia 
is  the  immediate  consequence.  In  the  same  way  if  the  cerebellum 
is  no  longer  in  anatomical  and  physiological  connection  with  the 
cerebrum,  the  involuntary  movements  become  disordered.  Ac- 
cording to  the  conception  of  Adler  the  influence  of  the  cerebellum 
is,  above  all,  inhibitory. 

Is  THERE  REASON  TO  DISTINGUISH  Two  ORGANS  IN  THE 

CEREBELLUM — THE  CEREBELLAR  CORTEX  AND  THE 

CENTRAL   GRAY  NUCLEI? 

Anatomically  and  histologically  the  cerebellar  cortex  presents 
itself  with  a  structure  and  character  so  special  that  it  constitutes 
an  organ  highly  differentiated,  and  very  distinct  from  the  central 
gray  nuclei.  In  the  cerebellum,  as  in  the  cerebral  hemispheres, 
the  cortex  and  the  central  gray  nuclei  are  looked  upon  as  distinct 
organs. 

Between  the  cortex  and  the  central  gray  nuclei  (dentate  nu- 
cleus, nucleus  of  the  roof,  globulus  and  embolus),  there  are  inti- 
mate relations  through  the  intermediation  of  the  projection  fibers. 
They  take  their  origin  in  the  cerebellar  cortex  and  terminate  in  the 
nuclei  (Andre-Thomas).  One  can,  therefore,  represent  the  cere- 
bellar cortex  as  the  point  of  departure  of  the  excitations  which 
will  transform  themselves  into  tonic  variations  by  passing  through 
the  central  gray  nuclei  and  the  centers  with  which  they  are  in 
connection. 

Physiologically,  the  cerebellar  cortex  comports  itself  differ- 
ently from  the  central  gray  nuclei.  The  destructions  of  the  cor- 
tex are  translated  by  symptoms  which  are  less  grave,  and  less 
enduring,  than  those  destructions  which  affect  the  deeper  organs. 


THE    CEREBELLUM    AND   MOTILITY  199 

The  cerebellar  cortex  is  not  excitable,  whereas  the  central  gray 
mass  is  (Horsley). 

Horsley  and  Clarke  have  shown  besides  that  the  cortex  and 
the  nuclei  have  a  very  different  influence  upon  the  contractures  of 
animals  which  have  been  decerebrated.  In  a  first  group  of  ex- 
periments these  authors  sectioned  the  mid-brain  in  a  dog  and 
produced  a  generalized  rigidity  which  was  due  to  the  interrup- 
tion of  the  cerebral  influx.  In  removing,  by  successive  layers, 
the  cerebellum,  these  authors  noted  that  this  hyper-tonicity  did 
not  commence  to  recede  until  the  moment  the  section  intersected 
the  intrinsic  nuclei,  and  the  para-cerebellar  nuclei  (probably  the 
nuclei  of  the  vestibular  nerve).  In  another  group  of  .experi- 
ments, they  separated  by  a  massive  horizontal  section,  the  dorsal 
half  of  the  cerebellar  cortex,  and  three  weeks  later  they  sectioned 
the  mid-brain.  In  this  case,  the  rigidity  of  the  decerebrated  ani- 
mals did  not  differ  from  that  of  normal  dogs. 

The  cerebellar  cortex,  therefore,  is  not  indispensable  for  the 
maintenance  of  contracture.  and  the  principal  source  of  the  motor 
impulses  of  the  rigidity  is  the  central  gray  nuclei  and  the  para- 
cerebellar  nuclei.  (Thiele  arrived  at  the  same  conclusions.) 
According  to  Horsley  and  Clarke,  the  cerebellar  cortex  is  a  re- 
ceptive center  of  impressions  from  the  trunk  and  from  the  limbs 
of  a  special  character,  always  coordinated. 

According  to  Sherrington,  the  contractures  consecutive  to  de- 
cerebration  can  be  inhibited  by  the  excitation  of  the  anterior  sur- 
face of  the  cerebellum.  Faradization  of  this  region  is  followed 
by  a  relaxing  of  the  muscles  of  the  neck,  the  head,  and  the  hind 
legs,  more  particularly  on  the  side  of  the  excitation.  This  author 
thinks  that  the  cerebellum  has  an  inhibitory  influence. 

Do   LOCALIZATIONS   EXIST  IN   THE   CEREBELLUM? 

This  question  should  be  studied  separately  for  the  cerebellar 
cortex,  and  for  the  central  gray  nuclei. 

One  can  only  accept  with  great  reserve  the  results  obtained 
by  excitation  of  the  cerebellar  cortex,  since  the  excitability  of  the 
cortex  is  disputed,  and  even  denied  by  some  physiologists,  such 
as  Horsley  and  Clarke.  As -to  the  destructions  of  the  cortex, 
they  generally  only  give  rise  to  temporary  disturbances  unless  they 


2OO  THE   FUNCTIONS   OF   THE   CEREBELLUM 

are  widespread.  Some  authors  maintain,  however,  that  they  have 
obtained  very  localized  symptoms  by  the  destruction  of  very 
limited  regions  of  the  cortex. 

After  the  destruction  of  the  most  internal  portion  of  the 
crus  primum  (terminology  of  Bolk),  Marassini  observed  abnor- 
mal movements  of  the  front  leg  of  the  same  side.  They  were 
lacking  if  this  region  remained  uninjured,  even  when  the  lesion 
of  the  lateral  lobe  was  more  widespread.  The  destruction  of  the 
most  internal  portion  of  the  crus  secundum.  and  of  the  para- 
median  lobe  is  followed  by  abnormal  movements  of  the  hind  leg 
of  the  same  side. 

Von  Rynberk  observed  also  disturbances  of  motility  in  the 
front  legs,  which  were  realized  constantly  and  exclusively  when 
the  crus  primum  of  the  anciform  lobule  was  destroyed.  The 
concomitant  lesion  of  the  lobule  simplex  only  caused  an  increase 
of  the  intensity  and  the  duration  of  these  effects.  There  exists 
a  center  for  the  muscles  of  the  neck  in  the  lobule  simplex :  a  local- 
ized lesion  of  this  level  has,  for  a  consequence,  rotatory  instability 
of  the  head. 

After  destruction  of  the  ansiform  lobule  in  the  goat,  Vincen- 
zoni  did  not  observe  any  anomaly,  but  if  the  lobule  simplex  were 
simultaneously  destroyed  he  observed  ambulatory  dysmetria 
("  gait  of  a  cock "),  in  the  anterior  homolateral  limb.  The  resec- 
tion of  the  lobule  simplex  in  which  he  got  no  results  from  the 
dog,  had,  as  a  consequence,  a  complete  but  temporary  suppression 
of  locomotion.  With  the  suppression  of  the  paramedian  lobe, 
movements  of  rotation  around  the  longitudinal  axis  appeared. 
The  doctrine  of  cerebellar  localizations  is  also  accepted  by  Hul- 
shoff  Pol,  and  by  Rothmann.  According  to  Hulshoff  Pol  the 
suppression  of  the  posterior  median  lobe  in  the  dog  gives  rise  to 
incoordination  in  the  hind  limbs;  that  of  the  paramedian  lobe, 
besides  ataxic  symptoms,  pleurosthotonus  and  peculiar  gait,  which 
he  calls  the  "  walk  of  parade."  After  destruction  of  the  crus 
secundum  of  the  ansiform  lobe  he  observed  ataxia  and  the  "  gait 
of  a  cock." 

The  experiments  of  Rothmann  were  made  upon  the  dog  and 
the  monkey.  The  unilateral  resection  of  the  quadrangular  lobe 
(lateral  segment  of  the  lobule  simplex  and  crus  primum  of  the 
ansiform  lobule)  in  the  dog,  was  followed  by  a  disturbance  in  the 


THE    CEREBELLUM    AND   MOTILITY  2O I 

position  of  the  front  leg  of  the  same  side.  The  paw  was  held  to 
one  side  and  behind  its  normal  position ;  the  fore  paw  was  turned 
over  and  the  animal  did  not  draw  it  back  when  it  hung  over  the 
edge  of  the  table.  Disturbances  of  the  same  type  occurred  in 
the  hind  leg  after  destruction  of  the  crus  secundum  of  the  ansi- 
form  lobule,  which  corresponds  to  the  semilunar  lobe.  In  the 
monkey,  lesions  limited  to  the  cortex  of  the  quadrangular  lobe 
occasioned  disturbances  limited  to  the  homolateral  anterior  limb. 
Movements  of  the  hand  and  the  fingers  were  awkward,  and  were 
accompanied  by  a  fine  tremor,  and  the  arms  were  put  into  an 
exaggerated  flexion.  These  phenomena  diminished  gradually,  but 
still  persisted  at  the  end  of  a  month.  They  were  more  marked 
in  both  limbs  when  the  two  quadrangular  lobes  were  destroyed. 
Locomotion  remained  unaffected.  When  the  destruction  was  car- 
ried to  the  semilunar  lobe,  similar  disturbances  appeared  in  the 
posterior  limbs. 

The  authority  of  the  physiologists  who  have  made  these  ex- 
periments gives  them  a  real  value ;  and  although  the  results  do  not 
absolutely  agree,  they  favor  the  idea  of  functional  localizations  in 
the  cerebellar  cortex.  We  must  await  the  confirmation  of  these 
results  by  new  researches. 

As  to  the  central  gray  nuclei  they  could  be  decomposed  into 
special  centers,  if  one  takes  into  account  the  experiments  of 
Clarke  and  Horsley  cited.  One  may  remark,  however,  that  the 
excitation  of  the  central  gray  substance  of  the  cerebellum  is  a 
very  difficult  experiment  to  perform,  and  that  it  is  very  difficult 
to  say  from  which  of  the  nuclei  of  the  cerebellum,  and  of  the 
neighboring  nuclei,  the  excitation  comes. 

It  is  necessary  to  make  some  reservations  as  to  the  existence 
of  precise  localizations  in  the  cerebellar  cortex — only  taking  into 
account  the  results  of  experiments.  One  cannot  affirm  the  func- 
tional unity  of  the  cerebellar  mantle.  On  the  contrary,  ana- 
tomical facts  permit  us  to  suppose  that  the  vermis  and  the  hemi- 
spheres have,  in  relation  to  one  another,  a  certain  independence. 
The  vermis  is  phylogenetically  older  than  the  lateral  lobes.  It 
represents,  in  a  way,  the  primitive  cerebellum,  the  cerebellum  of 
the  animals  whose  brain,  or,  rather,  whose  cerebral  cortex  is  still 
rudimentary,  and  in  whom  the  movements  of  the  limbs  are  still 
only  slightly  differentiated.  The  lateral  lobes  are  altogether 


2O2 


THE   FUNCTIONS    OF   THE   CEREBELLUM 


rudimentary  in  certain  birds,  and  in  reality  do  not  make  their 
appearance  except  in  mammals,  and  for  each  species  they  are 
developed  according  as  it  occupies  a  higher  place  in  the  animal 
scale.  They  attain  a  maximum  importance  in  those  animals 
whose  cerebrum  itself  is  very  highly  developed,  and  the  move- 
ments of  whose  limbs  is  the  most  differentiated. 


FIG.  85.  Vertico-transverse  section  of  the  pons  and  the  cerebellum,  in 
a  case  of  crossed  atrophy  of  the  cerebellum  due  to  a  lesion  of  the  right 
cerebral  hemisphere  dating  from  infancy.  To  the  right  the  path  of  the 
crus  cerebri  is  degenerated  (PY).  On  the  left  it  is  intact.  The  atrophy 
of  the  left  cerebellar  hemisphere  affects  the  convolution  of  the  lateral  lobe, 
the  white  substance,  and  the  cerebellar  olive.  The  central  bundle  of  the 
tegmentum  (Fee)  is  atrophied  on  the  right.  In  this  case  there  was  an 
atrophy  of  the  medullary  olive  on  the  right.  (Consequently  crossed  tin 
relation  to  the  cerebellar  atrophy.)  (Thomas  and  Cornelius,  Revue 
Neurologique,  1905.) 

When  the  cerebral  cortex  is  destroyed  over  a  large  area  of  the 
motor  zone,  and  particularly  when  the  optic  thalamus  is  at  the 
same  time  injured  or  atrophied,  a  crossed  hemi-atrophy  of  the 
cerebellum  results  (Figs.  85,  86  and  87).  This  hemiatrophy  is 


THE    CEREBELLUM    AND    MOTILITY 


203 


very  frequent  when  the  cerebral  lesion  dates  from  infancy  (and 
in  this  case  not  only  the  cortex  is  atrophied,  but  the  cells  of  Pur« 
kinje  are  lacking  in  the  corresponding  regions)  ;  this  may  be  found 
also  in  the  adults  (Figs.  88  and  89),  but  less  constantly,  and  in  a 
less  marked  degree.  It  has  been  observed  in  animals  which  have 
suffered  grave  cerebral  mutilations  during  the  first  weeks  of  their 
lives  (Von  Monakow),  The  crossed  hemiatrophy  of  the  cere- 


rn. 


FIG.  86.  Transverse  section  of  the  tegmentum  pontis  in  a  case  of 
crossed  atrophy  of  the  cerebellum  due  to  a  lesion  of  the  cerebral  hemi- 
sphere dating  from  infancy.  Atrophy  of  the  left  cerebellar  peduncle  (Pcs). 

bellum  affects  the  lateral  lobe  of  the  cerebellum  and  respects  the 
vermis  (Andre-Thomas  and  Cornelius).  In  the  lateral  lobe  it 
has  a  certain  predilection  for  the  quadrilateral  lobe. 

The  atrophy  of  the  superior  cerebellar  peduncle  can  be  fol- 
lowed as  far  as  the  dentate  nucleus  even  in  adults.  It  depends 
upon  the  atrophy  of  the  optic  thalamus.  The  atrophy  of  the  cere- 
bellar cortex,  of  the  middle  cerebellar  peduncle,  and  the  white 


2O4 


THE    FUNCTIONS   OF   THE   CEREBELLUM 


substance,  is  the  consequence  of  the  degeneration  of  the  pedun- 
cular paths,  and  its  interrelation  with  the  gray  substance  of  the 
pons. 

The  pathogenesis  of  crossed  hemiatrophy  has  been  very  much 
debated.  Some  have  attributed  it  to  a  functional  inactivity, 
others  to  a  secondary  transneural  atrophy.  Against  the  first 
theory  the  fact  may  be  invoked  that  crossed  atrophy  of  the  cere- 
bellum is  rarer  and  less  marked  in  the  adult  than  in  the  child, 
whereas,  the  functional  activity  of  the  cerebellum  should  attain  its 
maximum  in  the  first  case. 


Crst 


M 


ae. 


FIG.  87.  Transverse  section  of  the  medulla.  In  a  case  of  crossed 
atrophy  of  the  cerebellum  dating  from  infancy.  Crossed  atrophy  of  the 
medullary  olive  (O/)  (see  Figs.  85  and  86). 

The  explanation  is  of  little  importance.  The  main  point  is, 
the  intimate  association  of  each  cerebral  hemispere  with  the  cere- 
bellar  lobe  of  the  opposite  side,  and  the  subordination  of  the  latter 
to  the  former.  The  cerebral  cortex  of  the  fronto-parietal  and 
temporal  regions  is  projected  upon  the  cortex  of  the  opposite 
lateral  lobe  of  the  cerebellum,  and  slightly  also  upon  the  homo- 


THE   CEREBELLUM    AND    MOTILITY  20$ 

lateral  lobe,  by  the  intermediation  of  the  cerebral  crus  and  the 
pontine  nuclei,  while  the  spino-medullary  centers  are  projected 
upon  the  cortex  of  the  vermis.  The  efferent  fibers  of  the  vermis 
are  exclusively  directed  to  the  terminal  nuclei  of  the  vestibular  root 
of  the  auditory  nerve,  and  by  their  intermediation  to  the  medulla 
and  the  spinal  column;  the  efferent  fibers  of  the  hemispheres 
go  partly  to  the  red  nucleus,  and  partly  to  the  thalamus,  and  the 
thalamus  transmits  their  excitations  to  the  cerebral  cortex.  This 
is  why,  basing  oneself  upon  comparative  anatomy,  normal  anat- 
omy, and  pathological  anatomy,  we  must  consider  the  vermis  and 


FIG.  88.  Atrophy  of  the  right  crus  cerebri  (F),  and  of  the  pyramid 
(Py).  Atrophy  of  the  left  cerebellar  hemisphere.  For  the  other  indica- 
tions see  the  figures  in  the  chapter  on  anatomy. 

the  lateral  lobes  as  functionally  different  regions,  not  having 
the  same  attributes.  We  are  able  therefore  to  distinguish  two 
systems:  The  cerebro-cerebellar,  or  hemispheric  system,  and  the 
medullo-spino-cerebellar  or  vermian  system.  We  must  consider 
all  the  lessions  seated  in  the  paths  of  the  first  system,  as  hav- 
ing manifestations  of  the  same  kind,  as  would  all  the  lesions 
seated  in  the  paths  of  the  second  system.  In  future  attention 
should  be  drawn  to  this  point. 

Whatever  it  may  be,  the  activity  of  each  cerebellar  hemisphere 
is  intimately  connected  with  that  of  the  opposite  cerebral  hemi- 
sphere ;  whereas,  that  of  the  vermis  is  subordinated  to  that  of  the 


2O6 


THE   FUNCTIONS   OF   THE   CEREBELLUM 


spinal  column  and  the  medulla.  Perhaps,  also,  one  might  main- 
tain that  the  vermis  and  the  hemispheres  have  an  identical  func- 
tion, varying  in  its  intimate  mechanism  according  to  the  type  of 
animal  considered.  The  appearance  and  the  development  of  the 
cerebellar  hemispheres  are  only  witnesses  of  the  subordination 
of  the  inferior  centers  to  the  cerebral  influence  in  superior  verte- 
brates ;  nevertheless,  anatomy  teaches  that  in  this  class  of  animals 
there  is  a  manifest  independence  between  the  vermis  and  the  hem- 


FIG.  89.  Crossed  atrophy  of  the  cerebellum  in  a  case  of  cerebral 
hemiplegia  in  an  adult.  Above  the  superior  surface.  Below  the  anterior 
surface. 

ispheres  (Horsley  and  Clarke).  This  is  why  it  seems  more  prob- 
able that  the  vermis  and  the  lateral  lobes  do  not  have  absolutely 
identical  functions.  The  first  would  be  more  particularly  related 
to  the  functions  of  equilibration,  and  the  second  to  the  functions 
of  regulation. 

SUMMARY 

Among  the  results  of  experimental  and  clinical  investigation, 
we  must  distinguish  a  group  of  concordant  and  a  group  of  dis- 
cordant facts. 


THE   CEREBELLUM    AND    MOTILITY  2O/ 

The  first  group  consists  of  the  phenomena  produced  by  the 
destruction  of  the  organ.  The  second  group  of  those  produced 
by  its  excitation.  This  last  group  should  be  again  studied  before 
we  can  make  any  definite  physiological  deductions. 

The  symptoms  following  the  destruction  of  the  cerebellum  are 
above  all  disturbances  of  motility,  whether  the  movement  is  reflex, 
automatic  or  voluntary. 

The  motor  perturbation  affects  not  only  each  movement  con- 
sidered alone  but  also  the  association  of  movements,  or  better,  the 
motor  synergies. 

Each  movement,  isolated  by  itself,  is  not  incoordinate  as  in 
locomotor  ataxia.  It  is  characterized  by  dysmetria  and  discon- 
tinuity. When  the  movement  relates  to  the  maintenance  of  an 
attitude,  there  is  instability  or  astasia. 

The  disturbances  of  the  motor  synergies  are  particularly  man- 
ifested in  tonic  reactions  applied  to  the  maintenance  of  equilib- 
rium. There  is  a  perturbation  of  the  reactions  of  equilibration. 
The  cerebellum  perfects  and  accelerates  the  reestablishment  of 
equilibrium,  in  the  same  way  that  it  renders  movement  precise 
and  regular. 

The  cerebellum  assures  the  measure  and  the  continuity  of 
movement,  stability,  and  the  reactions  of  equilibration  by  a  special 
tonic  action.  This  regulatory  action  is  governed  partly  by  the 
cerebrum,  and  partly  by  peripheral  excitations,  but  it  is  not  a 
center  of  conscious  sensibility. 

We  cannot  but  look  upon  the  action  of  the  cerebellum  on 
muscular  tonus,  and  on  the  centers,  as  braking  or  inhibitory, 
rather  than  excito-motor.  It  is  probably  either  one  or  the  other. 
Is  not  the  cerebral  cortex  at  the  same  time  excito-motor  and  in- 
hibitory (Hering  and  Sherrington)  ?  By  the  excitations  of  the 
cerebral  cortex  have  not  physiologists  obtained  at  the  same  time 
contractions  of  certain  muscles  and  inhibition  of  the  tonus  of 
their  antagonists? 

Contrary  to  the  cerebrum,  the  influence  of  the  cerebellum  is 
exercised  principally  upon  the  muscles  of  the  same  side  of  the 
body. 

In  the  same  way  as  after  the  suppression  of  the  cerebellum, 
the  motility  of  the  limbs  is  not  abolished,  so  the  function  of 
equilibrium  is  not  definitely  lost.  It  may  be  reacquired,  in  a  cer- 
tain measure,  thanks  to  cerebral  and  labyrinthine  substitutions. 


2O8  THE   FUNCTIONS   OF   THE   CEREBELLUM 

The  existence  of  individualized  centers  of  differentiated  or 
coordinated  movements  in  the  cerebellum,  is  not  yet  absolutely 
demonstrated,  but  researches  in  this  line  up  to  now  are  rather 
favorable  to  this  hypothesis.  One  must  distinguish  two  organs 
in  the  cerebellum,  the  cortex  and  the  central  gray  nuclei.  In  the 
cortex  we  must  admit  a  certain  function  of  independence  between 
the  vermis  and  the  hemispheres.  The  same  is  the  case  for  the 
various  central  gray  nuclei. 

The  vermis,  or  primitive  cerebellum,  is  principally  in  relation 
with  the  inferior  centers  (spinal,  medullary,  pontine)  ;  the  hemi- 
spheres with  the  superior  centers  (cerebral  cortex,  central  gan- 
glia of  the  cerebrum).  The  action  of  the  cerebellum  may  be  ex- 
ercised either  through  a  reflex  path  (nucleus  of  the  vestibular 
nerve,  red  nucleus),  or  through  the  intermediation  of  the  cere- 
brum (superior  cerebellar  peduncle  and  thalamo-cortical  fibers). 

The  vermis,  the  relations  of  which  are  very  intimate  with  the 
nuclei  of  the  vestibular  nerve,  is  more  particularly  adapted  to  the 
regulation  of  the  coordinations  upon  which  the  equilibrium  and 
the  station  of  the  body  depend ;  the  hemispheres  to  the  regulation 
of  voluntary  movements. 


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INDEX 


Adiadochokinesis,  119 
Ageneses,  104 
Alar  fold,  43 
Anthropoid  apes,  49 
Anterior  vermis,  3 
Appendices,  lateral,  48 
Astasia,  155 
Asthenia,  155 
Asynergia,  123 
Ataxia,  labyrinthine,  193 

peripheral,  119 

cerebellar,  143,  154 

heredito-cerebellar,  12 
Atonia,  155 
Atrophies,  107 
Atrophy,  lamellar,  114 

olivo-ponto  cerebellar,  107 

Babinski,  phenomenon  of,  125 
Bechterew's  nucleus,  10 
Benedikt,  syndrome  of,  130,  178 
Beri-beri,  114 
Birds,  45 

destruction  of  c.  in,  81 
Bolk,  nomenclature  of,  52 
Bundles,    cerebellar    vestibular,    30, 
152 

Centrifugation,  196 
Centrifuging  action,  190 
Coitus,  61 

Corpora  quadrigemini,  i 
Corpus  dentatum,  I 
rhomboideum,  i 

Dendrites,  7 
Diadochokinesis,  119 
Dynamic  nystagmus,  127 
Dysmetria,  118 

Electrical  stimulation,  85 


Equilibration,  169 
Equilibrium,  coarse,  176 
fine,  176 

Fibers,  afferent,  II 

internal  arciform,  33 

of  association,  9,  10,  42 

of  Cajal,  9 

centrifugal,  II 

centripetal,  9 

climbing,  9 

descending  cerebellar,  40 

intrinsic  cerebellar,  40 

cortico-pontine,  26 

efferent,  27 

olivary,  20 

peduncular,  9 

of  projection,  9,  10,  40 

thalamo-cortical,  28,  152 
Fishes,    destruction    of    cerebellum 

in,  80 

Flocculus,  5 

Flourens,  theory  of,  162 
Folium  cacuminis,  5 

Gait,  jumping,  67 

"  Gait  of  a  cock,"  199 

Golgi,  multipolar  cells  of,  8 

Granular  layer,  6 

Gyrus  post-centralis,  160 

Hemiatrophy,  crossed,  203 
Hemiparesis,  161 
Hemiplegia,  103 
Hemispheres,  cerebellar,  5 
Hemorrhage,  101 
His,  fundamental  fold  of,  43 

rhomboidal  lip  of,  44 
Hypotony,  158 

Inferior  vermis,  3 


221 


222 


INDEX 


Jugal  segment,  44 
Juxta-restiform  body,  30 

Kake,  114 

"  Kleinhirn,"  I 

Labyrinth,  187 
Labyrinthine  ataxia,  193 

otitis,  193 

representation,  178 

tonus,  iys 
Lamellae,  5 
Lobe,  central,  5 

digastric,  5 

of  lingula,  5 

of  nodule,  5 

of  the  culmen,  5 

of  the  declive,  5  , 

of  uvula,  5 

paramedian,  42 

superior  semilunar,  5 
Lobes,  5 

lateral,  3 

median,  3 

primordial,  5 
Lobules,  5 
Lobus  gracilis,  5 
Localizations  in  cerebellum,  199 

Macacus,  76,  97 
Micturition,  6 
Molecular  layer,  6 
Movements,  clonic,  167 

tonic,  II 

Muscular  sense,  141 
Myxine,  45 

Neocerebellum,  3 
Nodule,  5 

Nuclei,  para-cerebellar,  90 
Nucleus,  arciform,  24 

Deiter's,  10,  30,  152 

emboliformis,  I 

fastigii,  I,  10 

globosus,  I 

magno-cellularis,  30 

of  Bechterew,  30 


Nucleus,  of  von  Monakow,  10 
parvo-cellularis,  30 
pre-pyramidal,  24 
reticularis  tegmenti,  28 
triangular,  30 

Olive,  cerebellar,  10 
Opisthotonus,  147 

Paleocerebellum,  3 

Peduncle,    inferior    cerebellar,     10, 

35,  95 

middle  cerebellar,  10,  22,  98 
superior  cerebellar,  27,  99 

Pigeon,  46 

Pons  Varolii,  I 

Posterior  columns,  10 
vermis,  3 

Pre-pyramidal  bundle,  29 

Purkinje  cell,  6 

Pyramid,  5 

Reflex  movements,  168 
Reil,  median  fillet  of,  102 

right  fillet  of,  102 
Reptiles,  45 

destruction  of  c.  in,  80 
Restiform  body,  II 
Root  of  Roller,  32 
Rubro-spinal  bundle  of  Monakow, 
160 

tract,  29 

Sclerosis,  multiple,  99 
Sexual  instinct,  132 
Softening,  101     • 
Special  senses,  136 
Spino-cerebellar  tracts,  93 
Strychnism,  psychic,  92 
Superior  cerebellar  peduncle,  10 

vermis,  3 
Swimming,  62 
Syndrome  of  Benedikt,  178 
Synergy,  169 

Tonsils,  5 


INDEX  223 

Tract  of  Burdach,  n  Valvulae,  tuber,  5 

direct  cerebellar,  n,  15.  16                Vermin    '-i 

of  Goll,  ii  Vertigo,  galvanic,  88 

of  Cowers,  n,  13,  16  of  Meniere,  193 

Tremor,  cerebellar,  121  rotatory,  194 

kinetic,  122  Vestibular  apparatus,  194 

static,  122  bundle,  30,  152 

Tiirck,  bundle  of,  26  Volition,  inertia  of,  176 

Uncus,  bundle  of  the,  34  Wernekinck,  decussation  of,  27 
Uvula,  5 


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